Department: Engineering and Applied Science: Civil Engineering ![[clear]](close-x.png "Remove this limiter")
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1.
Abdel Moteleb, Moustafa.
Risk Based Decision Making Tools for Sewer Infrastructure Management.
Degree: PhD, Engineering and Applied Science: Civil Engineering, 2010, University of Cincinnati
► Wastewater utilities in the United States face an aging workforce, higher consumer…
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▼ Wastewater utilities in the United States face an aging workforce, higher consumer expectations, stricter environmental regulations, security concerns, and an aging infrastructure. As a result, many utilities have turned to Asset Management for better decision making to prioritize their needs. According to numerous studies that were conducted in the past decade, most notably the USEPA Clean Water and Drinking Water Infrastructure GAP Analysis Report and the ASCE Report Card, wastewater utilities will need to invest approximately 390 billion in capital infrastructure over the next two decades. Meanwhile, the field of Asset Management is emerging to improve the decision making process to renew, replace, or rehabilitate the infrastructure. Asset management can be defined as set of activities, guidelines, and decision tools that seek to minimize the life cycle costs of capital and O and M spending while maintaining an acceptable minimum level of service (USEPA 2006). This research provides a road map for the implementation of asset management in wastewater utilities with a strong focus on the critical tools that are needed to identify, quantify, and manage risk associated with the structural failure of sewers. The two components of the Business Risk Exposure; namely the probability and consequences of failure were thoroughly evaluated. Criticality matrices for linear assets were developed using expert opinion. A GIS based criticality tool was developed to identify the most critical assets. The GIS model was developed to eliminate biases and establish a systematic methodology to quantify the impact of failure of an asset. Subsequently, maps were generated showing the critical sewers that the utility needs to focus its efforts on to reduce its risk exposure. Probability curves of sewer failure were developed using historical data extracted from repair history performed between 1997 and 2009. Closed Circuit Television (CCTV) condition assessment methodologies are the basis for the development of deterioration curves used by academics in the U.K., the U.S., Australia, and Canada. Condition based methodologies that are dependent of CCTV data are resource intensive and their output is subjective. The methods employed in this research to determine the probability of pipe failure are independent of CCTV of the assets. Deterministic models using polynomial regression analysis were developed to describe the deterioration of sewers with age. Probabilistic models were utilized using data fitting and Monte Carlo simulation. Soft computing methods were also used under this research by developing General Regression Neural Network Deterioration Models (GRNNDM) to predict the probability of sewers failure with age.
Advisors/Committee Members: Salem, Ossama.
Subjects: Sanitation
Keywords: asset management; sewers; deterioration models; infrastructure management; risk based decision making; criticality assessment
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2.
Alemayehu, Dawit.
Development of New Material Model for Reinforced Concrete under Plane Stress and its Application in the Modeling of Steel Frames with Reinforced Concrete Infill Walls.
Degree: PhD, Engineering and Applied Science: Civil Engineering, 2012, University of Cincinnati
► A rational, mechanics-based constitutive model for reinforced concrete in a state of…
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▼ A rational, mechanics-based constitutive model for reinforced concrete in a state of plane stress is developed. The model accommodates the possibility of formation of multiple crack sets if the maximum tensile stress direction deviates by at least 30 degrees from existing crack orientations. Contribution of crack sliding/ opening motion to total strain is also taken into consideration. Reinforcing bars follow a linear elastic model with hardening as suggested by Menegotto and Pinto, with the modification that at crack interfaces the capacity of reinforcing bars to resist compression is reduced. Plain concrete follows a damage-based orthotropic material law. Stress-displacement relations at crack interfaces are modeled by simpler approximations of the Walraven's aggregate interlock principle formulas. The panel model is implemented for ‘mixed loading' and ‘strain control' conditions. ‘Mixed loading'â„¢ refers to the case where normal stresses and shear strain are prescribed, and normal strains and shear stress are computed. ‘Strain control' involves the specification of the three strain components from which the three stress components are derived. Shear stress-strain relations derived from the model display reasonably close comparisons with those of experiments. Cyclic axial and shear behavior of reinforced concrete panel are successfully modeled. The material model for reinforced concrete under plane stress conditions is successfully implemented in the open source finite element program OpenSees (Open System for Earthquake Engineering Simulation). The tangent stiffness method for cracked and uncracked cases is employed. The material model is used to simulate reinforced concrete wall tests, and the results are found to be in acceptably close agreement with those of experiments. The applicability of the material model in the simulation of steel frames with reinforced concrete infill walls is explored. Nonlinearity in steel frame is accounted for using the concentrated plasticity concept with the moment-rotation relation in accordance with the modified Ibarra-Krawinker model. Initially, a steel frame with partially restrained (PR) connections and a reinforced concrete infill wall tested at the University of Minnesota is modeled by assuming rigid beam-column connections. Comparison of total drift from the model with experiments indicates close agreement at earlier stages of loading. The frame was subsequently modeled accounting for the presence of PR connection. At earlier stages of loading, there is very little difference in response with respect to the fully restrained connection case. Convergence problems do not allow the modeling of steel frames with reinforced infill wall over the entire range of the experiment.
Advisors/Committee Members: Rassati, Gian.
Subjects: Engineering
Keywords: reinforced concrete infilll walls; nonlinear finite element
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3.
Barber, Melinda A.
Contribution of Shear Connections to the Lateral Stiffness and Strength of Steel Frames.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► Spurred by the abundance of welded moment connection failures observed in the…
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▼ Spurred by the abundance of welded moment connection failures observed in the Northridge earthquake of 1994, research efforts involving the capacity of simple gravity connections have since increased significantly. Typically, a building includes more gravity connections than moment connections, yet the moment resistance contributions of the gravity connections are neglected in design. Based on the lack of complete building collapse resulting from the Northridge earthquake, this paper analytically investigates the overall lateral stiffness and strength contributions of the system’s shear connections. This paper first investigates the differences between fully restrained (FR), partially restrained (PR) and simple shear connections. Next, previous experimental test setups and results are examined. Finally, ETABS finite element modeling techniques including an elastic hinge analysis and pushover analyses using both default and user-defined hinge parameters are compared. PR hinge properties for three experimental gravity connections will be explicitly defined. To allow application to a broader spectrum of gravity beam sizes, equations to define the PR hinge will be developed using properties of the beam. Ultimately, a prototype building will be modeled in ETABS for two different connection layouts. Once using the traditional shear connections, and again by replacing the shear connections with the PR connections previously defined by hinges. Comparing lateral drifts of these two models will provide quantification of the shear connection’s overall lateral stiffness contribution.
Advisors/Committee Members: Swanson, James.
Subjects: Civil Engineering
Keywords: shear connection; gravity connection; simple connection; partially restrained (PR) hinges; steel frames; stiffness
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4.
Edalath, Sanooj Sadique.
Fuzzy Logic Seismic Vibration Control of Buildings.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2012, University of Cincinnati
► Earthquakes have proven to be very disastrous to the mankind costing thousands…
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▼ Earthquakes have proven to be very disastrous to the mankind costing thousands of lives and billions of dollars worth property damage. Making earthquake resistant structures have always been a challenge to engineers. Researchers have come up with numerous strategies to build earthquake resistant structures. Implementing control devices in structures is one among those strategies which has proven to be effective and worthwhile. Control devices can be broadly classified into four categories, namely, passive, active, hybrid and semi active. The purpose of this research is to develop semi active controls by varying the damping coefficient of a passive control device in a controlled manner using an algorithm based on fuzzy logic. First, a semi active fuzzy logic based Tuned Mass Damper (TMD) is developed and tested on a one storey structure subject to free and forced harmonic vibrations and its performance is compared with a passive TMD with the same parameters. Comparison is also made between these two TMDs by testing them on a 15 storey structure for the same kind of vibrations. Later these TMDs are tested on a number of one storey structures with different fundamental frequency subject to Kocaeli earthquake motion and their performance is again compared. This way, the effectiveness of TMDs to resist earthquake vibrations in a structure is studied along with establishing the superior performance of a fuzzy TMD over a passive TMD. Base isolators have proven to be a better passive control device compared to TMDs in suppressing earthquake induced vibrations in a structure. This research also attempts to develop a fuzzy logic based semi active base isolator that outperforms the current state of the art semi active base isolator which uses a control algorithm which is of bang-bang in nature. Tests are done on a two degree of freedom structure for four different earthquakes, namely, El Centro, Hachinohe, Kobe and Northridge with these two controllers and the performance of the developed controller is compared to the performance of the controller discussed in the literature to establish the superior performance of the new controller. Finally, recommendations are made on what else can be done for further research and how this fuzzy logic based semi active controllers can be further improved.
Advisors/Committee Members: Kukreti, Anant.
Subjects: Civil Engineering
Keywords: Fuzzy logic; Seismic; Controls; Structures; TMD; Base isolators
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5.
Hantouche, Elie.
Behavior Of Thick Flange Built-up T-stub Connections For Moment Resisting Frames.
Degree: PhD, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► The primary goal of this research is to widen the applicability of…
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▼ The primary goal of this research is to widen the applicability of T-stub connections by investigating the behavior of thick-flange built-up T-stubs needed for deep beams which meet the prequalification requirements for moment-resisting-frames (MRF). Oftentimes the heavy rolled profiles needed to fabricate the T-stub for such deep beams are not immediately available to fabricators and so built-up sections are the only alternative. In this study, finite element (FE) simulations and experimental testing are used to provide the data set needed to develop mathematical models to describe the behavior of thick-flange T-stub connections. First, results obtained from plates tested to evaluate the influence of the hole fabrication practices show that standard drilled or standard flame cut can be used in detailing T-stub connections. Thick-flange T-stub components tested to establish design guidelines and to detail full-scale specimens for prequalification in MRF used with deep beams show that both thick-flange T-stub components built-up either by complete joint penetration (CJP) or fillet welds are acceptable. The T-stub component tests results are also used to validate the prediction of the load-deformation behavior up to failure obtained from three dimensional (3D) FE models. A failure limit state is highlighted, which is partial yielding at the K-zone followed by bolt fracture, with or without prying. Second, using the results from a parametric study, cases for thick-flange T-stub connection geometries needed for deep beams ranging from W24 to W36 sections are identified, and 3D FE models are developed. Using FE results, two separate prying strength models for thick-flange T-stubs with CJP and fillet welds are developed. The models are validated by comparing with FE results obtained for connections designed for W24 to W36 beams. Third, a modified stiffness model based on a combination of mechanistic approach modified with FE results is presented. The connection response is modeled on the basis of beam representation for the flange, multi-linear spring for the bolt forces, nonlinear torsion spring at the K-zone to account for the partial yielding, and accounting for contact phenomenon. The model shows excellent agreement with finite element results obtained for the same full-scale connections considered for the prying strength study. Fourth, 3D FE models were extended to include the column-side of the connection. The results are used to evaluate the effect of secondary prying in the T-flange/column-flange systems with and without continuity plates. Criteria for providing continuity plates is developed to guide the designer in the detailing process. For the cases studied, a model that quantifies the amount of total prying is developed. Finally, a 3D FE model is presented to obtain the global monotonic moment-rotation curve of a thick-flange built-up T-stub beam-to-column connection. The FE results exhibited the required rotation and moment for special-moment-frames and conform with the governing failure mode as per design. The FE results of rolled T-stub connection designed as full-strength show good agreement with existing experimental results. The experimental and analytical studies are used to refine the existing design methodology for thick-flange T-stub connections which provides designers a workable option for practical application.
Advisors/Committee Members: Kukreti, Anant.
Subjects: Civil Engineering
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6.
Hassan, Aleef.
Reuse of Petroleum Contaminated Soil in Pavement Construction.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► This study explores the possibility of using PCS in the surface layer…
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▼ This study explores the possibility of using PCS in the surface layer of asphalt pavements. It looks into engineering aspects like stability, flow, air void content, unit weight, and VMA percentage of asphalt specimens containing petroleum contaminated soils (PCS). The variation in the engineering properties of the asphalt concrete was studied with incorporating different percentages of PCS into it and also with a variety of asphalt contents. Change in the quantity of PCS in the asphalt specimen's results in a significant change in properties of asphalt concrete. This thesis looks into the change in properties of asphalt concrete with the addition of different percentages of PCS. A high content of PCS is expected to result in low stability of the mix. One way to meet the test specifications for mix having high PCS is by adding admixtures. Addition of different admixtures like limestone dust and fly ash results in improved engineering properties. This study also looks into the possibility of adding materials like fly ash to the same mix thereby enhancing the engineering properties of the mixes and at the same time getting rid of materials like fly ash. A set of laboratory tests were needed to establish the change in the properties of the asphalt mix with change in PCS and admixture contents. The Marshall test method (ASTM D-1559-82) is used to determine the stability, flow, and air voids of the mixes. This method was used to study the variation in properties of the mixes with the addition of contaminated soils and admixtures. From the test results, it can be concluded that PCS can be incorporated to hot mix asphalt because the asphalt mixes satisfy ODOT specifications for stability and flow even after adding 15% of PCS. Mixes with more than 7.5% of PCS do not satisfy the ODOT requirements for air voids and VMA for high traffic surface course. This study clearly indicates that more than 7.5% of PCS cannot be added to the mix as it results in very low air voids. It is also found that with the addition of PCS the amount of asphalt cement required in the mix is reduced. This can result in very high savings. It is also seen that 2% of fly ash can be added to the mix, satisfying the ODOT specifications. This will result in effective disposal of fly ash, which is detrimental to environment.
Advisors/Committee Members: Ioannides, Anastasios.
Subjects: Civil Engineering
Keywords: Petroleum Contaminated Soil; Hot Mix Asphalt; Contaminated Soil Reuse
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7.
Hauber, Robert J.
Finite element analysis of an integrally molded fiber reinforced polymer bridge.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► A finite element model of a fiber reinforced polymer (FRP) bridge in…
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▼ A finite element model of a fiber reinforced polymer (FRP) bridge in Hamilton County, Ohio was conducted using the computer program SAP2000. The purpose of the model was to determine the vertical deflection under a specified truck loading and to compare the analytical results from the model with load test results of the actual bridge, which spanned approximately 20 feet. The bridge superstructure was composed of eight separate panels that were assembled on site. The panels were constructed of a sandwich panel deck with integral beams spaced approximately two feet on center with the panels themselves being approximately seven and a half feet wide. The finite element model utilized shell elements to represent the different FRP components of the bridge such as the top and bottom faces of the deck along with the beam webs and flanges. The material properties input into the model for the shell elements were provided by the manufacturer. A mesh sensitivity analysis was conducted to identify an adequate discretization of the bridge without creating an excessive amount of elements in the model. Once this was accomplished, the entire bridge was then modeled with the applied loading to mimic the truck loading tests to which the actual bridge was subjected in order to assess the validity of the finite element model. The results of the model showed good agreement with the experimental results, validating the model.
Advisors/Committee Members: Miller, Richard.
Subjects: Civil Engineering
Keywords: fiber reinforced polymer; finite element analysis; bridge; shell elements; mesh sensitivity
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8.
Itekyala, Sudhir Reddy.
Vehicle Classification under Congestion using Dual Loop data.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2010, University of Cincinnati
► The growing congestion problem on Interstates has been identified as a serious…
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▼ The growing congestion problem on Interstates has been identified as a serious problem for accurate data collection from automatic sensors like Inductive loop detectors (ILD). Traffic speed and vehicle classification data are typically collected by dual-loop detectors on freeways. During congestion, measurement of vehicle lengths which is based on detector ON and OFF timestamps (raw loop event data) often lead to misclassification of vehicle data. Accurate detection of raw event data and modified classification algorithm are increasingly important for higher data accuracy needs for agencies such as Advanced Traffic Management Systems (ATMS) and Advanced Traffic Information Systems (ATIS). Vehicle classification algorithm works on the assumption of constant vehicle speed in the detection area. This assumption is violated during congestion which induces errors in to vehicle length estimates leading to more inaccurate vehicle classification data. This paper unlike in preceding works presents a model which is simple enough to be implemented using existing loop detector hardware. This new model assumes vehicle travels with constant acceleration over loop detection area and thus named as ―Constant Acceleration based Vehicle Classification model (CAVC)‖. This model first identifies traffic flow state and later uses Kinematic equations for estimating vehicle length values. Data is collected by videotaping dual loop station and also simultaneously collecting raw loop event data. Ground truth vehicle data is then extracted using Vehicle Video-Capture Data Collector (VEVID) [Wei et al. 2005] from video data. This improved model (CAVC model) is then validated using ground truth classification data and also compared with the results from existing vehicle classification model for different traffic flow states (under specific scenarios).
Advisors/Committee Members: Wei, Heng.
Subjects: Civil engineering
Keywords: vehicle classification; interstate congestion; dual loop detectors
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9.
Joy, Emmanuel.
Comparison and Study of Load and Resistance Factor Rating (LRFR) and Load Factor Rating (LFR) Methods.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► The Load and Resistance Factor Rating (LRFR) method developed by extending the…
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▼ The Load and Resistance Factor Rating (LRFR) method developed by extending the Load and Resistance Factor Design (LRFD) philosophy, relies on structural reliability methods to provide a uniform reliability to the evaluation of bridges. Improved analysis methods and incorporation of site specific data in LRFR provides more realistic and rational predictions of the bridge condition. Lower maintenance and repair costs, less costly traffic restrictions, and more reliability in public safety are expected to be achieved. LRFD has been recognized as the primary method for designing of bridges by the Federal Highway Administration, set to replace Load Factor Rating (LFR) or Allowable Stress Rating (ASR) methods, which are bridge evaluation methods based on Load Factor Design (LFD) or Allowable Stress Design (ASD) methods. Due to the large number of bridges built with LFD and ASD methods still in use and the large number of engineers familiar with the LFR and ASR methods of load rating, even for bridges designed using LRFD, the transition to LRFR has not been made mandatory with the Manual for Bridge Evaluation (2008) providing all three methods of rating the bridges. A comparative study of the methods can achieve greater insight to the differences in the methods and the causes for that. It would also help in refining the LRFR methodology if improvements are deemed necessary. The thesis studies the effect of inclusion of site specific data and the distribution factor equations on the difference in LRFR and LFR values. The influence of condition factor accounting for increased uncertainty due to deterioration is observed. The avenues for better accounting of system effect of bridges are identified. The results also show the importance of inventory and operating level of load rating in facilitating the transition from LFR and ASR and at the same time charting the course for LRFR methodology in bridge evaluation.
Advisors/Committee Members: Swanson, James.
Subjects: Civil Engineering
Keywords: Bridge; LRFR; LFR; Load Rating
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10.
Kulkarni, Allakh.
An Application of Strut-and-Tie Model to Deep Beams.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► Strut-and-tie modeling (STM) is an experimentally proven technique to analyze and design…
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▼ Strut-and-tie modeling (STM) is an experimentally proven technique to analyze and design D-regions. STM is easy to model if the truss configuration is available. The flow of forces and stresses within the beam can be visualized with STM, and an appropriate truss can be assembled to represent the stress pattern. The required reinforcement to resist the tension at different locations can be detailed from the forces in the truss members. The study presented herein analyzes and designs deep beams subjected to point loads and uniformly distributed loads. Beams with high-strength as well as normal-strength concrete were modeled in this study. The clauses from ACI 318 (2008) are followed throughout this research. Strut-and-tie technique is an iterative process. MATLAB programs were written to perform the iterative calculations. The output from the MATLAB programs includes the longitudinal reinforcement as well as shear reinforcement required to resist the applied loads on the beam. The cases considered herein included simply supported beams subjected to single or two point loads. The loads were placed symmetrically as well as asymmetrically. The output from the MATLAB programs was verified with the software CAST. The results from MATLAB were found to be in agreement with CAST output. A comparative study between two different models proposed in literature was performed and the results were included to justify the selection of a particular model in this research. An attempt was made in this research to generate an optimum design. The design was subjected to a large number of iterations. These iterations generated an optimum truss height and, hence, the most efficient deign for the given beam properties. The strut-and-tie model considered in this research requires design of shear reinforcement as well as reinforcement to resist the transverse tensile force in the bottle shaped struts. The required reinforcement to resist the two actions (shear and transverse tension) was detailed such that excessive use of bars was avoided. The detailing of the longitudinal reinforcement was performed in a manner that would ensure ease of field installation. Preference was given to straight developed bars and smaller diameter bars. Similarly, large diameter bars were avoided as shear reinforcement. Adequate space was ensured within the bars from the same layer, with adjacent layers and shear reinforcement to facilitate concreting of the section.
Advisors/Committee Members: Shahrooz, Bahram.
Subjects: Civil Engineering
Keywords: Strut-and-tie Model; Deep Beams
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11.
Leben, Tyler J.
Moment Redistribution of Continuous Hybrid Highway Bridge I-Girders Fabricated from HPS-100W Steel.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2012, University of Cincinnati
► Moment redistribution from interior piers to adjacent spans of straight continuous span…
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▼ Moment redistribution from interior piers to adjacent spans of straight continuous span bridge girders is an alternate inelastic design procedure, Appendix B6 of the AASHTO LRFD Bridge Design Specifications (AASHTO 2010) that was formerly known as autostress design prior to the 2004 AASHTO Specification (Kayser 2005). This alternative inelastic design procedure recognizes that there is additional capacity beyond the elastic range of the material; when this additional capacity is recognized, localized yielding and inelastic rotation occurs at the section of maximum moment, over an interior pier of a continuous span (Kayser 2005). Moment at this location is automatically relocated or redistributed to the adjacent spans that generally have a lower moment demand (Kayser 2005). Once the moment has been redistributed, a more balanced moment envelope is obtained (Kayser 2005). The reduction in the maximum moment allows the section over the interior pier to be designed for a smaller moment, resulting in a reduced section, fatigue details, material weight, and fabrication costs (Kayser 2005). This research investigated if Appendix B6 of the AASHTO LRFD Bridge Design Specifications (AASHTO 2010) is an acceptable method for predicting inelastic behavior of a typical single full-length continuous steel hybrid highway bridge I-girder fabricated from HPS-100W flanges and conventional steel webs, with specified minimum yield strength of 100.0 ksi and 50.0 ksi., respectively. Through finite element modeling, it was found that AASHTO (2010) predictions for moment-rotation behaviors are similar for a full-length continuous steel hybrid highway bridge I-girder fabricated from HPS-100W flanges and conventional steel webs, with specified minimum yield strength of 100.0 ksi and 50.0 ksi, respectively. However, further investigation is required to determine if a maximum allowable plastic rotation should be inflicted to prevent the possibility of rupture of the flange. In addition, this research investigated if varying the grade of steel that the flanges of a hybrid section are fabricated from has an effect on the shear demand on the crossframes in a bridge system. Three different hybrid girder configurations were considered. Each configuration consisted of a top and bottom flange fabricated from one grade of steel and the web fabricated from A572 specified minimum yield stress of 50.0 ksi. The flanges were either material grade HPS-100W with a specified minimum yield stress of 100.0 ksi, HPS-70W with a specified minimum yield stress of 70.0 ksi, or A572-50 with a specified minimum yield stress of 50.0 ksi. Through finite element modeling, it was found that shear demand in the crossframes do not differ by a significant amount due to the change in grade of steel in the flanges of the hybrid section with 50.0 ksi grade steel in the webs. Therefore, the lateral moment redistribution is assumed to be comparable to the characteristics of lateral moment redistribution that is exhibited by lower grade materials.
Advisors/Committee Members: Swanson, James.
Subjects: Civil Engineering
Keywords: High Preformance Steel; Steel Bridge; HPS-100W; Inelastic; Moment Redistribution; Shear Demand on Crossframes
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12.
Li, Zhixia.
Dynamic Dilemma Zone Modeling and Its Protection.
Degree: PhD, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► As a major cause of crashes at high speed signalized intersections, the…
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▼ As a major cause of crashes at high speed signalized intersections, the issue of dynamic yellow light dilemma zone (DZ) has been raised by researchers for many years. However, quantitative study of the inherent factors contributing to the DZ dynamics remains an issue, especially for Type I dilemma zone and option zone. In this context, this research aims at quantitatively modeling the dynamic nature of DZ through investigating contributing factors to Type I and Type II dilemma zones, respectively. To fulfill this goal, video data collection has been conducted at four high speed signalized intersections in Ohio. Qualified trajectory data of 1445 vehicles have then been extracted from 46-hour digital videos using customized software program VEVID. Results of statistical analyses of the vehicle trajectory data have quantitatively revealed that the driver’s minimum perception-reaction time (PRT) is a function of speed, while the maximum deceleration and acceleration rates are functions of both speed and the aggregated 85th percentile speed of the intersection approach. On the other hand, results of binary logistic regression analyses have indicated that lane position, vehicle type, posted speed limit, duration of yellow interval, and speed gap between following vehicles are significant contributing factors that influence driver’s stopping probability, in addition to vehicle’s speed and location at the onset of yellow indication. These findings have successfully revealed and modeled the dynamics of Type-I and Type II DZs, and have provided theoretical basis for updating the existing DZ models to reflect DZ’s dynamic characteristics. As a solution to safety issues caused by DZ, the optimal advance detector placement method for DZ protection has been specifically developed based on the updated dynamic DZ model resulted from this research. The optimization process is conducted in a calibrated microscopic traffic simulation test bed. The optimization objective is to minimize the combined cost of the traffic conflicts due to the existence of DZ, which represent the safety, and the delay experienced by drivers, which represents the mobility. Specifically, the probability of traffic conflicts is assessed by dilemma conflict potential (DCP), which is a comprehensive surrogate dilemma hazard model proposed in this research. Unlike the traditional surrogate dilemma hazard measure of “number of vehicles in DZ”, DCP quantitatively computes the combined probability of rear-end and right-angle conflicts faced by each vehicle that approaches the intersection during the yellow interval. The computation is based on both the speed and the location information of a target vehicle and its leading vehicle with regard to the locations of DZ as well. The DCP model has been calibrated by using field-observed trajectory data before its use in the optimization process. Finally, the generated optimal advance detector placement method has been evaluated with comparison to other four classic placement methods which are widely used in the US. The evaluation results have proved that the optimal method is superior to Bonneson, Beirele, SSITE, and Winston-Salem layouts by greatly reducing the combined cost of dilemma hazard and delay, which indicates it can provide effective and efficient protection to dynamic DZ.
Advisors/Committee Members: Wei, Heng.
Subjects: Engineering
Keywords: Dilemma Zone; Driver's Stopping Behavior; Loop Placement Method; Yellow Light; Safety; Operations
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13.
McElhone, Ian R.
A Systems Approach to Instrumentation Selection for Monitoring Cable Stayed Bridges.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► Bridges are a critical component of the nation's infrastructure, easing the transport…
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▼ Bridges are a critical component of the nation's infrastructure, easing the transport of people and goods where roadways on land are not available. These structures are exposed to vehicular and environmental load effects which cause deterioration and a reduction in the structural capacity. This wear and tear was highlighted by the recent I-35W Bridge collapse in Minneapolis, Minnesota. This failure highlights the importance of the Federal Highway Administration's mandate that all bridges be regularly inspected and load rated every two years. Continuous monitoring of existing bridges has been implemented by the Ohio Department of Transportation officials to meet these requirements. The Ironton-Russell cable stayed bridge replacement is a structure that has been selected for structural health monitoring. The monitoring system is particularly critical for the Ironton-Russell Bridge because it is a cable stayed design and behaves in a very complex manner. The Ohio Department of Transportation has contracted a research team at the University of Cincinnati to design the instrumentation package for the bridge. The monitoring system will capture the deterioration of the structure and provide a more accurate measurement of the structural capacity for the entire life of the bridge. This thesis presents a comprehensive report of the monitor design process and the load rating of the Ironton-Russell Bridge's structural components.
Advisors/Committee Members: Swanson, James.
Subjects: Civil Engineering
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14.
McIntosh, Sean P.
Factors Impeding the Advancement of Straw Bale As a Feasible and Sustainable Construction Building Material in North America.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► Building systems may achieve an integration of affordability, green construction, and sustainability…
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▼ Building systems may achieve an integration of affordability, green construction, and sustainability through the utilization of straw-bale construction. This building method may be particularly beneficial to countries that are characterized by developing economies or are enduring a recovery from a natural disaster. Employed as a means to replace or complement traditional building materials, straw-bale construction provides easy installation and energy efficiency. Conventional and prescriptive building regulations create a barrier to the widespread advancement of straw-bale construction. Specifically, common and standardized materials exist in capital intensive industries that compete against each other in a market that can support testing. These factors provide difficulty in introducing and establishing new and competitive building materials. Similarly, preconceived notions of straw-bale construction methodology, design limitations, and supposed deficiencies in straw bales as a feasible building material must be overcome. The exploratory study undertaken herein developed an evaluation of those factors that are impeding the development of this construction methodology in North America. The goal of the study is to provide an analysis of what is the general consensus from builders, contractors, engineers, and architects regarding straw-bale construction. The primary research methods included surveying building professionals throughout North America to gauge their perceptions and experiences. Furthermore, a Life Cycle Assessment (LCA) was conducted to measure the environmental impact of a straw-bale home as compared to a home utilizing common building techniques. Such results may be utilized to facilitate the advancement of this affordable and sustainable construction material.
Advisors/Committee Members: Shahrooz, Bahram.
Subjects: Civil Engineering
Keywords: straw-bale construction; sustainability; alternative construction materials; energy effeciency; Life Cycle Assessment (LCA)
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15.
Melam, Madhu Chandra.
Development of Rating Scale in Lean Construction.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► In the United States, construction companies / industry have been trying to…
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▼ In the United States, construction companies / industry have been trying to introduce new practices in order to stay competitive. Lean Construction is one of these practices which attempts to reduce cost by eliminating unnecessary activities. Lean practices have been adapted by the construction industry, but there is no rating system to measure the how well lean tools are applied in construction. This thesis details the development of a scale for rating the implementation of lean construction tools for a given construction project. Key initiatives (major lean tools) which are to be rated have been determined through literature review. All the lean tools are then taken equally and the degree of implementation is rated on a scale of 1 to 10. The sum of the ratings gives an overall score. A case study is presented to give an example of how the developed model can be used. A critique of the case study shows examples of how implementation of lean tools can be improved.
Advisors/Committee Members: Miller, Richard.
Subjects: Civil Engineering
Keywords: lean construction; rating scale
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16.
Nemalapuri, Vijay Krishna.
Impact of Traffic Operations on Carbon Monoxide Emissions Analysis.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2010, University of Cincinnati
► US EPA stipulates the use of MOBILE6.2 for air conformity of transportation…
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▼ US EPA stipulates the use of MOBILE6.2 for air conformity of transportation projects in accordance with State Implementation Plan (SIP). Use of local data for modeling project level emissions have a large impact on the magnitude and distribution of estimated and/or predicted emissions, and it can also significantly influence the accuracy of local scale air quality modeling assessments. The results from emission factor analysis show that the volume of traffic and day of week are not related to emission factors while they are highly influential in determining overall emissions at the level of roadway infrastructures. Moreover, MOBILE6.2 is limited in application for modeling emissions by variation in traffic operations. This issue can be addressed by using vehicle operation specific variable, or called vehicle specific power (VSP). Many previous studies have indicated that road grade, instantaneous speed, and acceleration of vehicles are three main contributing factors to the estimation of VSP. VSP represents the instantaneous power per unit mass of the vehicle and is dependent on vehicle characteristics. This is either obtained experimentally in lab or by using formulae (both mechanistic and empirical). The emission factors obtained from MOBILE6.2 are overlapped with experimental data of instantaneous vehicle specific power data to generate new operation specific emission factors. It is observed that idling and running operations of vehicles are more precisely defined by using VSP bins. In this study, method for estimating the impact of traffic operation on mobile source emission via VSP is explored. To set up an exemplary study case, the roadways surrounding the west campus of University of Cincinnati (UC) were selected for analysis of VSP and Carbon Monoxide (CO) emissions. Emission factors are higher during fall after school has started, when compared with summer due to large number of medium to heavy vehicles moving around, change in age distribution and diurnal traffic patterns. Winter brings in large temperature variations which had large impact on emission factors in addition to above mentioned parameters. Air quality analysis is performed over limited periods to time to validate the emission analysis that was performed. CAL3QHC has under predicted the CO concentrations at receptors. Results have shown that un-skewed data (71% of total data) has a RMSE of 1.106, Fractional Bias range of 0.1 to 1.8, Index of Agreement of 0.718, NMSE1 of 0.015 and NMSE2 of 0.017. The main issue was observed with the skewness of dataset and more data points are recommended for this analysis.
Advisors/Committee Members: Wei, Heng.
Subjects: Civil engineering
Keywords: emissions analysis; mobile source emissions; vehicle specific power; traffic operations; emission factors
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17.
Nirmalkumar, Deepika.
Evaluation of Current Drivers, Challenges and State of Art in Risk Treatment and Asset Management Planning for a Sewer District.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► When the stakeholders of a particular sector participate in every control related…
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▼ When the stakeholders of a particular sector participate in every control related session with inputs that are wide and varied; narrowing down the final choices can become an exhausting situation. Current work environment in the construction and infrastructure industry calls for precise decisions with the capacity to deliver them on time. Although this ideology is much appreciated by strategists, it is sometimes not in the interest of the utility to rush up into deliverables not recalling the long term effects. In keeping with the growing need for well-informed cost engineering economics; the risks of faulty decisions are costly and limit protection to the entrepreneur. The goal of this research is to bring together various aspects of risk consideration by generating a logic flow pattern for utility operations. It also links critical aspects of asset management and project prioritization methods. The proposed methodology includes a direction in this regard along with informative reports on sewer systems and their processes as inputs for good decision making. The term risk management (RM) can sometimes be interpreted in numerous ways. The characterization of RM used in this thesis is under the umbrella of risk assessment, modeling, planning and management including the fractions about contingency planning and management. This thesis presents an overview of comprehensive theory and practices performed by analysts and the corresponding management protocols for utility operators. While people who truly deal with risk are well aware of the limitations of current technologies, they are also keen on extracting as much worthy information as possible. This calls for a well formulated background discussion of the various risk management programs and policies for sewerage utilities.
Advisors/Committee Members: Miller, Richard.
Subjects: Civil Engineering
Keywords: risk assessment; risk treatment; sewer management; wastewater collection
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18.
Ruffley, Daniel J.
A Finite Element Approach for Modeling Bolted Top-and-Seat Angle Components and Moment Connections.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► A verified procedure for modeling bolted top and seat angle components and…
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▼ A verified procedure for modeling bolted top and seat angle components and connections for potential use in seismic moment frames using finite element analysis software is presented here. The vast usage of top and seat angle connections in moment frames would fall into the range of partially restrained connections. This type of connection is not currently certified to be used by engineers for moment resistance in any major building specification jurisdiction. The main reason for this is the complex analysis required of a structure to take advantage of such a connection effectively, to say nothing of the complex analysis also necessary on the connection level. However, these connections have been demonstrated to provide economic savings should the engineer invest into these analyses. This work is tailored to aid engineers in analysis on the connection level. The modeling procedure was used to recreate two full-scale top and seat angle connection tests as well as multiple component tests. Load – displacement values from FEA model analyses were compared to experimental data and verified. Mechanistic observation also indicated agreement in the modes of failure of the FEA models with the experimental tests. Given the lack of variety in the failure modes of top and seat angle connections and their components, some of the component tests recreated were t-stub component tests to illustrate the accuracy, precision, and confidence of the modeling procedure. The following failure methods were able to be predicted: tension bolt failure, shear bolt failure, and block shear failure. A beam sensitivity analysis was also performed early in the study that accurately demonstrates the ability to predict the formation of plastic hinge phenomena. All models were created using hexahedral solid elements utilizing reduced integration with either eight or twenty nodes. This modeling procedure so verified could be used as a tool by engineers in preliminary analysis and design stages to alleviate the daunting task of building such a model and analysis from scratch.
Advisors/Committee Members: Rassati, Gian.
Subjects: Civil Engineering
Keywords: finite element analysis; bolted connection; top and seat angle; seismic; moment frame; experimental full scale test
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19.
Ruffley, Daniel J.
A Finite Element Approach for Modeling Bolted Top-and-Seat Angle Components and Moment Connections.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► A verified procedure for modeling bolted top and seat angle components and…
(more)
▼ A verified procedure for modeling bolted top and seat angle components and connections for potential use in seismic moment frames using finite element analysis software is presented here. The vast usage of top and seat angle connections in moment frames would fall into the range of partially restrained connections. This type of connection is not currently certified to be used by engineers for moment resistance in any major building specification jurisdiction. The main reason for this is the complex analysis required of a structure to take advantage of such a connection effectively, to say nothing of the complex analysis also necessary on the connection level. However, these connections have been demonstrated to provide economic savings should the engineer invest into these analyses. This work is tailored to aid engineers in analysis on the connection level. The modeling procedure was used to recreate two full-scale top and seat angle connection tests as well as multiple component tests. Load – displacement values from FEA model analyses were compared to experimental data and verified. Mechanistic observation also indicated agreement in the modes of failure of the FEA models with the experimental tests. Given the lack of variety in the failure modes of top and seat angle connections and their components, some of the component tests recreated were t-stub component tests to illustrate the accuracy, precision, and confidence of the modeling procedure. The following failure methods were able to be predicted: tension bolt failure, shear bolt failure, and block shear failure. A beam sensitivity analysis was also performed early in the study that accurately demonstrates the ability to predict the formation of plastic hinge phenomena. All models were created using hexahedral solid elements utilizing reduced integration with either eight or twenty nodes. This modeling procedure so verified could be used as a tool by engineers in preliminary analysis and design stages to alleviate the daunting task of building such a model and analysis from scratch.
Advisors/Committee Members: Rassati, Gian.
Subjects: Civil Engineering
Keywords: finite element analysis; bolted connection; top and seat angle; seismic; moment frame; experimental full scale test
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20.
Salman, Baris.
Infrastructure Management and Deterioration Risk Assessment of Wastewater Collection Systems.
Degree: PhD, Engineering and Applied Science: Civil Engineering, 2010, University of Cincinnati
► Proper collection and transmission of wastewater within pipe systems is of utmost…
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▼ Proper collection and transmission of wastewater within pipe systems is of utmost importance to minimize public health problems and environmental contamination resulting from discharge of untreated sewage. However, due to reactive management strategies, overall condition status of wastewater systems has reached a sub-standard level. Moreover, budget restrictions due to competing needs are preventing sewer agencies from addressing inspection and repair/renewal of every deficient pipe. Therefore, sewer agencies are in dire need of establishing risk assessment tools in order to optimize use of limited resources by prioritizing inspection and/or renewal needs of sewer pipes. The objective of this dissertation is to develop such a risk assessment tool at an individual pipe level by combining the probability of failure values determined by statistical deterioration modeling of sewer pipes and consequences of failure values determined by examining the geographical, physical, and functional attributes of sewer pipes in the light of expert opinions that reflect the relative importance of these attributes. In order to determine probability of failure values, three statistical methods, namely ordinal regression (proportional odds model), multinomial logistic regression, and binary logistic regression, were employed in successive steps. Five ordinal regression models were generated by using logit, probit, negative log-log, complementary log-log, and cauchit link functions. Proportional odds assumption of ordinal regression was tested for each model; however, due to unsatisfactory results, ordinal regression was excluded from further analysis. Based on the percentage of correct predictions, binary logistic regression was deemed to be the most suitable method for predicting probability of failure. Consequences of failure values were determined based on a weighted scoring system. This method was selected due to uncertainties associated with direct costs of sewer failures and the intangible nature of social and environmental impacts of sewer failures. Expert opinion was obtained from a local sewer agency to evaluate geographical, physical, and functional attributes of pipes in terms of consequences of failure. Three methods were employed in order to assess risk of failure: multiplication, risk matrices, and fuzzy inference systems. The multiplication method helped differentiate pipes with similar probability of failure values but different consequence of failure and vice versa. However, this method failed to distinguish pipes having low probability of failure accompanied with high consequence of failure from pipes having high probability of failure accompanied with low consequence of failure values. Use of risk matrices overcame the aforementioned limitation of the multiplication method by allowing different levels of risk values to be assigned to different combinations of probability and consequence of failure values. On the other hand, the discrete nature of the variables in risk matrices caused inaccurate representation of risk values near boundary levels of probability and consequence of failure values. Finally, fuzzy inference systems were used to represent the fuzziness in probability, consequence and risk of failure variables; and to assign risk values based on fuzzy rules. Based on the outcomes, the use of fuzzy inferences led to a better representation of failure risk of sewer pipes.
Advisors/Committee Members: Salem, Ossama.
Subjects: Civil engineering
Keywords: infrastructure management; wastewater collection systems; probability of failure; consequence of failure; risk assessment; fuzzy inference systems
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21.
Schippers, Jared D.
A Design Procedure for Bolted Top-and-Seat Angle Connections for Use in Seismic Applications.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2012, University of Cincinnati
► Since the 1994 Northridge and 1995 Kobe earthquakes, bolted moment connections have…
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▼ Since the 1994 Northridge and 1995 Kobe earthquakes, bolted moment connections have garnered considerable interest for their application in Seismic Lateral Resisting Systems (SLRS). However, the considerable amount of research conducted over the last two decades has not produced many design procedures that would allow the applications of bolted connections either as fully-restrained or partially-restrained. This paper outlines a step-by-step design procedure for the design of bolted top-and-seat angle moment connections for seismic applications. The proposed procedure is used to design three practical examples of top-and-seat angle connections: two full-strength and one partial-strength. The connections are then are modeled in ABAQUS following a validated modeling approach that has been verified against multiple experimental tests, both quantitatively and mechanistically. The analysis results of these models are subsequently compared to the expected outcomes from the design procedure, as a proof-of-concept. The results of this comparison are presented and commented on, and it is concluded that the proposed procedure is suitable for the design of bolted top-and-seat angle connections for seismic applications.
Advisors/Committee Members: Rassati, Gian.
Subjects: Civil Engineering
Keywords: moment connections; bolted connections; partially restrained; moment frames; finite element modeling; design procedure
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22.
Schrader, Craig A.
Prequalification and Design of Rolled Bolted T-stub Connections in Moment Resisting Frames.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2010, University of Cincinnati
► Implementation of moment frames as the primary Seismic Lateral Resisting System (SLRS)…
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▼ Implementation of moment frames as the primary Seismic Lateral Resisting System (SLRS) has become increasingly popular over the years due to their ability to create open layouts and long, uninterrupted spans. Welded connections were typically used to create the fully-restrained (FR) beam-to-column connection required in most moment frames, but ever increasing labor costs have led to the development of bolted T-stub connections as a financially viable option. Brittle failures of what was, at the time, considered an acceptable FR connection forced the American Institute of Steel Construction (AISC) to require pre-testing of all moment connections used in the SLRS in an attempt to ensure the predictability and safety of future structures. The specific testing requirements are outlined in ANSI/AISC 341-10 [1], and although preliminary results for rolled bolted T-stub connections appear favorable, this connection type has yet to be submitted to AISC's Connection Prequalification Review Panel (CPRP) for consideration. Data from previous experimental programs will be used to show the acceptability of rolled bolted T-sub connections and the final recommendation will be for rolled bolted T-stub connections to be prequalified for use in the SLRS of moment resisting frames.
Advisors/Committee Members: Rassati, Gian.
Subjects: Civil Engineering
Keywords: Steel; Connection; Frame; Seismic; Moment; Prequalification
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23.
Schroeder, John M.
Moment-Rotation Curves for Shear Tab Connections Using Finite Element Modeling and Experimental Data.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2012, University of Cincinnati
► This thesis presents the results of research into using finite element modeling…
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▼ This thesis presents the results of research into using finite element modeling software to create moment-rotation curves for "simple" gravity connections. In current design practice, the rotational stiffness of gravity connections is ignored to ease calculations and due to limited availability of data on the response of gravity connections to rotational demands. Research is presented that shows when the rotational stiffness of these connections is added to the lateral load resisting system, the building response to seismic effects is improved, with smaller associated story drifts and decreases to the moments experienced in the moment frames and in the gravity beams In an effort to increase the amount of data on the rotational stiffness of gravity connections available to researchers, this thesis presents the design of two theoretical shear tab connections. The finite element modeling software ABAQUS is used to create moment-rotation curves for these theoretical connections. To demonstrate finite element modeling's ability to accurately predict the response of the theoretical connections, the results of several experiments performed on shear tab connections are reproduced in ABAQUS. The finite element modeling of the experimental shear tab connections shows that this type of modeling is able to reproduce connection specific events such as bolt slippage, beam-column bearing, and shear tab failure. Additional research is presented indicating finite element modeling's ability to predict net section fracture and block shear rupture of connection components. Lastly, steps taken to create the finite element models of the theoretical shear tab connections are presented along with the final moment-rotation curves for the connections.
Advisors/Committee Members: Rassati, Gian.
Subjects: Civil Engineering
Keywords: shear tab; gravity connection; finite element; moment rotation curve; partially restrainted connection; structures
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24.
Sengupta, Abir K.
Instrumentation and Load Rating of Steel Curved Girder Bridges.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► Curved girder bridges are frequently used by state departments of transportation because…
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▼ Curved girder bridges are frequently used by state departments of transportation because they add significant flexibility in the determination of highway alignments, especially at congested interchanges. Much of the seminal research into the behavior of curved girder bridges was conducted in the late 1960s. The development of computer programs for the analysis and design of curved-girder bridges quickly followed and they have become more advanced over time. While the load path for a straight girder bridge is such that the girders are subjected primarily to shear forces and strong-axis bending moments, the load path in curved girders bridges inherently includes eccentric loads that result not only in strong axis shear forces and bending moments but also torsional moments, warping, and the resulting shear. As a result, the level of complexity in modeling a curved bridge is increased exponentially when compared to a straight bridge. A secondary consideration is the selection of girder configurations for curved-girder bridges. While I-shaped girders are often selected as the de facto section of choice for straight bridges, box girders offer significant advantages over I-shaped girders in curved bridges because of the relatively high torsional rigidity that they offer. This article addresses the most significant issues involved with the analysis and design of curved girder bridges starting with a review of the mechanics associated with torsion, which acts on the members, moving into a review of research conducted to date, which is then followed by a summary of design provisions. Next, the topic of finite element modeling of curved girder bridges in 2D and 3D will be addressed. Finally, a discussion of evaluation and load rating of curved bridges will be presented. As a final consideration, a study comparing the behavior of tangent bridges (bridges made up of straight girders supporting a horizontally curved roadway) with the behavior of curved bridges will be conducted and included in the thesis.
Advisors/Committee Members: Swanson, James.
Subjects: Civil Engineering
Keywords: Curved; Steel; Girders; Instrumentation
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25.
Stillings, Tyler W.
Load Distribution and Ultimate Strength of an Adjacent Precast, Prestressed Concrete Box Girder Bridge.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2012, University of Cincinnati
► A decommissioned, adjacent precast, prestressed concrete box girder bridge constructed in 1967…
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▼ A decommissioned, adjacent precast, prestressed concrete box girder bridge constructed in 1967 was load tested to destruction in August and September of 2010. The bridge, which crossed Paint Creek approximately nine miles (14.5 km) northeast of Washington Court House, Ohio, consisted of three simple spans, each 47 ft. 10 in. (14.6 m) long. Each span was comprised of nine, 21 in. (533.4 mm) deep by 36 in. (914.4 mm) wide prestressed concrete box beams for a total width of up to 27 ft. 4 in. (8.3 m) with a 15° left-forward skew. Prior to testing, the bridge appeared to be in good condition, with the vast majority of deterioration limited to concrete spalling from the exterior webs of the fascia girders. Of the three spans tested, this thesis details testing and analysis of the first two. In addition to environmental deterioration, the first span was damaged by researchers, whereas no additional damage was done to the second. Loads were applied via three, 350 kip (1557 kN) hydraulic cylinders supported by steel load frames. Test data collected from pressure transducers, wire potentiometers, and strain gauges were compared to predictions from a reinforced concrete modeling program. Beam capacity and bridge distribution factors were compared to values calculated from the AASHTO LRFD Bridge Design Specifications. Data analysis shows that the response of the bridge was predicted well by the analysis program for both low-level destructive and ultimate destructive loads. It was determined that bridge capacity could be found by summing the capacity of each individual beam, as long as the calculated capacity is reduced for the effects of damage. The bridge maintained its ability to transmit load between girders even after cracking of shear keys, indicating that steel tie rods play a major role in transmitting load from one beam to the next.
Advisors/Committee Members: Miller, Richard.
Subjects: Civil Engineering
Keywords: Prestressed concrete; Concrete box girders; Adjacent box girder bridge; Full-scale bridge test
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26.
Thimmapuram, Vinod-Kumar.
FINITE ELEMENT MODELING AND STUDY OF ANGLE CONNECTIONS.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2011, University of Cincinnati
► The recent 1994 Northridge and 1995 Hyogo-Ken earthquakes made the structural…
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▼ The recent 1994 Northridge and 1995 Hyogo-Ken earthquakes made the structural engineers to look for an alternate connection type to the fully welded connections, which failed to perform miserably under the nature’s seismic forces. This quest for an alternate connection type led the structural engineers to revisit the “Partially Restrained Connections (PRC)”, which exhibit sufficient ductility to dissipate the earthquake forces. Top and Seat Angle connection is one among the many PRC’s widely accepted and researched. The present study focuses on the various currently available prying models used to predict the capacity of angle connections. These include the prying model adopted by AISC design code (2005), the prying model used in Eurocode (2003), and Modified Struik Model by Swanson (2002). A comparison study is carried out to arrive at the prying model that predicts the capacity of the connection close to that obtained by performing a physical test on it and modification to the prying models is recommended to better the prediction of the capacity for a given angle connection. The experimental results on Top and Seat Angle connections reported by Abolmaali (1999) have been used in this study. In addition to the available experimental information on the Top and Seat Angle connections, static finite element analysis was performed on candidate selected angle connection configurations. This additional information on the connection behavior from the finite element analysis helped in substantiating the comparison study. Parameters defining the connection geometry were chosen and the test cases for performing the finite element analysis were formulated by looking at the different possible combinations of these geometric parameters, while taking into consideration the currently accepted design and fabrication requirements. A finite element software package ANSYS (6.1) was used to perform the finite element analysis on the connections.
Advisors/Committee Members: Kukreti, Anant.
Subjects: Civil Engineering
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27.
Zhang, Wei.
Study of the Influence of Gravity Connections on the Lateral Response of Steel-Concrete Composite Moment Frames.
Degree: MS, Engineering and Applied Science: Civil Engineering, 2012, University of Cincinnati
► Traditionally in the design practice of steel buildings, moment connections have been…
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▼ Traditionally in the design practice of steel buildings, moment connections have been considered as perfectly rigid for the purpose of resisting lateral loads with simple connections to resist gravity loads. Simple connections have been considered as perfectly pinned. Some research work with experimental tests have shown that simple connections perform neither as perfectly rigid nor as pinned, which was referred to as partially restrained or semi-rigid behavior. A series of tests performed by Liu and Astaneh (2000) were considered. In this research, composite shear tab connections showed properties of partially restrained connections. ETABS FEMA hinges were used to model the test results of one of the composite specimens. M3 type of hinge was chosen to be used to best model the moment-rotation behavior of composite connections. The results of backbone curve of moment-rotation from ETABS showed good agreement with the experimental test results. Several model buildings with proper ratios of number of gravity connections to the number of moment connections were checked. A prototype building was first designed as a bare steel building in ETABS to compare the results to the original design, in order to ensure that the results provided by ETABS were capable of reproducing a satisfactory design. Then a prototype building was designed as a composite building under the same loading conditions. From Liu and Astaneh’s tests, a moment connection model based on test results for composite shear tab connections was used to obtain the proper hinge parameters for the use in ETABS. Then two cases were compared, prototype building with pinned connections in gravity frames and prototype building with PR connections in gravity frames. Comparisons were made with respect to the following aspects: lateral displacement under the same lateral force, lateral force under the same lateral displacement, moment in moment frames and moment in gravity beams. As a result, the prototype building with PR connections in gravity beams showed larger stiffness. It could also be seen that the moment in moment frames was greatly decreased at the beginning of the application of lateral loads. This effect was reduced as the lateral force increased. Ultimately, PR connections acted as pinned. Simple connections which are traditionally modeled as pinned connections could be used as PR connections for the lateral resistance of a building structure.
Advisors/Committee Members: Rassati, Gian.
Subjects: Civil Engineering
Keywords: gravity connections; composite; lateral resistance; simple connections
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