Department: Engineering : Civil Engineering ![[clear]](close-x.png "Remove this limiter")
103 matches in the database.
These are records: 1 - 30.
Did you mean instcode:ucii?
[1] [2] [3] [4]
1.
ABU HAMAD, AYMAN ABDALLAH.
A DECISION SUPPORT SYSTEM FOR MANUFACTURED HOUSING PRODUCTION PROCESS PLANNING AND FACILITY LAYOUT.
Degree: PhD, Engineering : Civil Engineering, 2003, University of Cincinnati
► Productivity improvement of manufactured housing (MH) production systems has been a great…
(more)
▼ Productivity improvement of manufactured housing (MH) production systems has been a great concern to manufacturers and production managers. The evaluation of the production system efficiency in the factory is essential for meeting the growing demand of customers with respect to design and size of the manufactured housing product (MH). The purpose of this research is to resolve some of the problems of the MH production system. The problems of the existing system are identified in the masters thesis, Abu Hammad 2001, as follows: i) process bottlenecks hindering productivity, ii) unbalanced processes, and iii) layout limitations to the production capacity. Moreover, a lack of technology is observed in the existing MH operations. Existing production systems employing the traditional production line have low throughput and are inefficient. This dissertation research explores alternative layout designs that are proven via simulation to be more efficient and productive. Additionally, an advanced MH production system employing recent theories in technology and manufacturing is addressed in this research. The major contribution of this dissertation is to develop a decision support system (DSS), which provides the MH industry with an efficient tool to streamline the performance of existing MH facilities. This dissertation investigates the interrelation impact of multiple factors on the productivity of four modules: (i) market, (ii) factory, (iii) manufactured housing processes, and (iv) production system layout. The following objectives have been achieved in support of the stated goal: 1.Develop a streamlined MH process; 2.Develop optimization models to streamline the activities and predict relevant parameters; 3.Develop advanced layout designs employing recent theories in manufacturing (i.e., lean production theory). The DSS provides assistance in the following decisions: (i) selecting an efficient system layout matching user requirements, (ii) streamlining activities and operations of the overall production system, and (iii) predicting the productivity and product sizes based on the organizational requirements. Finally, a feedback from the manufacturers has indicated that the DSS meets a crucial need for streamlining the system operations. The proposed DSS is a practical, simple, and accurate tool for scheduling and planning the operations, resources, and material requirements of the production system.
Advisors/Committee Members: Salem, Dr. Ossama.
Keywords: Decision Support System, Manufactured Housing, Facility Layout, Production System, Simulation Modeling, Optimization, Productivity improvent, System efficiency
More Like This
2.
ABU HAMMAD, AYMAN ABDALLAH.
SIMULATION MODELING OF MANUFACTURED HOUSING PROCESSES.
Degree: MS, Engineering : Civil Engineering, 2002, University of Cincinnati
► This thesis is concerned with the production enhancement of the Manufactured Housing…
(more)
▼ This thesis is concerned with the production enhancement of the Manufactured Housing processes in construction. The Manufactured Housing industry in U.S.A. offers a good solution for the increasing demand on the low cost housing compared to the site built houses. The main objective of this research is to identify ways by which the productivity of a manufactured housing factory could be improved leading to a cost effective and efficient system. A manufactured housing factory provides a controlled arena for studying the manufacturing process and to develop ways of improving the productivity and efficiency of the system. To achieve the objective of this research, a through literature review was carried out in the field of Manufactured Housing followed by process data collection at two manufactured housing factories in Indiana. A simulation model was developed using Arena simulation software to study the production process and to determine process bottlenecks. The model describes the production line and the logical flow of the production unit in the factory. The simulation model is aimed to depict the reality in the factory. Arena software enables the modeler to simulate very sophisticated levels of activity relationships and also has the advantage of animating the simulation process. Hence, animation serves as a verification tool throughout the continuous development of the model. A comparison was done between the output measures of the model and the factory data to validate the simulation model. The simulation study identified several process bottlenecks that when present could limit the efficiency of the production process in a manufactured housing factory.
Advisors/Committee Members: Hastak, Dr. Makarand.
Keywords: Simulation, Modeling, Manufactured Housing, Assembly line, Construction processes
More Like This
3.
Acharjee, Tapas.
Investigating Accumulation of Tolerances and its Impact on Reliability of Job Site Installation.
Degree: MS, Engineering : Civil Engineering, 2007, University of Cincinnati
► Architecture-Engineering-Construction projects may account for product and process design tolerances within drawings…
(more)
▼ Architecture-Engineering-Construction projects may account for product and process design tolerances within drawings and specifications. However, as projects combine a series of components, these tolerances will accumulate. Failure to manage this accumulation can result in component misfits or poor quality of installed work, revealing a lack of product and process design integration. This thesis investigates how tolerance accumulation contributed to breakdowns in bleacher installation on a tennis court project. Building upon earlier work, we create product tolerance, process sequence maps, and generate a tolerance accumulation matrix for a bleacher module to identify components that have the greatest impact on job-site assembly. We discuss how to prevent breakdowns on future projects by restructuring work to enable predictable workflow and achieve better built-in quality. In particular, we explore how to introduce poka-yoke devices as well as changes in contracting, work sequencing, modularity, and new product development to achieve efficient delivery of bleacher systems.
Advisors/Committee Members: Tsao, Cynthia C.Y.
Subjects: Engineering, Civil
Keywords: Tolerances, Variability, Work Structuring, Constructability, Reliability, Product Design, Process Capability
More Like This
4.
Akomolede, Olusegun.
The Design and Building of a Geocone.
Degree: PhD, Engineering : Civil Engineering, 2009, University of Cincinnati
► The use of soil borings in soil investigation began decades ago. It…
(more)
▼ The use of soil borings in soil investigation began decades ago. It has developed from simple sampling tools used for digging holes in the ground and obtaining soil samples to more sophisticated means whereby a motorized drilling rig is used to bore holes in the ground to obtain soil samples. This method was further improved to include soil sampling and testing with a standard penetration split spoon sampler. Other boring and sampling means that have been developed in recent years include geoprobe sampling which involves continuously pushing a sampling tube into the ground to obtain continuous soil samples. In the last 50 to 70 years, the Dutch Cone penetrometer testing has been developed and has gained considerable popularity in the field of geotechnical study mostly in Europe but also in parts of the United States and Canada. This method involves pushing a conical shaped tool into the ground and reading the resistance encountered. While these two popular soil investigation means have been extremely popular and versatile in their use, each method on its own is limited in its reliability. For example, while soil samples can be readily obtained from soil borings, testing of the soil strength by the standard penetration testing method can sometimes be inaccurate and unreliable. This is because this test does not measure soil strength directly but relies on counting the number of blows required to hammer test spoon into the soil and judging the strength from the blow counts. With cone penetrometer testing, while the soil strength can be accurately and reliably measured, this method does not lend itself to any soil sampling. This gap is what the geocone is designed to bridge. Specifically, the geocone is designed as a geotechnical tool that combines the ability to take soil samples with testing of the soil strength in situ. It combines the basic function of a test boring with that of cone penetrometer testing. This research study starts with that basic concept and progresses into preliminary design of the tool. Choosing the type of materials and components suitable for the fabrication of the tools followed by the actual fabrication process are major steps in the geocone development. The next step involving the actual assembly and building of the tool forms another significant chapter in this research study. Lastly, the testing and calibration of the tool culminate the study. Each of the research steps is involved with different problems and challenges that have to be overcome. Many of the problems and challenges resulted in minor to major modifications to the design, material specification, fabrication, building and testing of the tool. The most significant of these challenges are discussed to give insight into the overall process involved in the accomplishment of the research goal. The geocone tool has been designed and built to adapt to author's existing equipment and drilling rigs. This adaptation was necessary to minimize the cost of the project. The geocone, when modified and adapted to a specific drilling rig which is designed and built to use the tool, may revolutionize the soil sampling and testing process in geotechnical engineering.
Advisors/Committee Members: Bowers, Mark T.
Subjects: Civil engineering; Environmental engineering
Keywords: design of a geocone; building of a geocone
More Like This
5.
ALLEN, JAMES H III.
EFFECTS OF SUBCOMPONENT ANALYSIS IN PREDICTING OVERALL STRUCTURAL SYSTEM DYNAMIC RESPONSE.
Degree: PhD, Engineering : Civil Engineering, 2007, University of Cincinnati
► An analytical methodology is developed that allows engineers to be able to…
(more)
▼ An analytical methodology is developed that allows engineers to be able to quickly incorporate structural modifications while minimizing error propagation through the use of subcomponent analysis. The effects of small modifications or changes are analyzed independently and then incorporated with existing structural behavior data through an analysis algorithm that has been developed, in order to predict the behavior of the integrated system. In the process, the research develops a system of governing differential equations that can be numerically solved more rapidly. While the new matrices may retain the same number of degrees of freedom as the original system, a larger number of values in the matrices representing the subcomponents have not changed and thus do not need to be recomputed. A comprehensive numerical basis is formulated utilizing the principles of finite difference and incremental analysis techniques. By utilizing existing data of a known discretization (mesh size), a relationship between the degree of structural modification, the discretization parameters of the modified region, and the expected error are developed for several classes of partial differential equations. Incremental difference equations are then developed that incorporate the linear and nonlinear behaviors of a structural system. A predictor between the expected error and discretization parameters of the modified subsystem are discussed. A substructuring technique is devised that utilizes the principle of superposition. In this research, a given structure is subdivided into two subsystems, “S” and “A” where “S” represents the domain of the structure that remains unchanged, while “A” represents the portion that has been either modified or newly added to the system. Both subsystems “S” and “A” are modeled as discrete systems using standard FEM procedures, and as such have a discrete number of common interface degrees of freedom, which form the boundary between the changed and unchanged portions of the overall new structure. In the methodology presented, the effects of the external forcing function acting on the system due to the effect of the modified subsystem are incorporated. Several case studies are then investigated to explore the behavior of different aspects of the structural models when analyzed using the proposed analysis algorithm. Finally, an example of a nonlinear structural system is analyzed and results are discussed.
Advisors/Committee Members: Kukreti, Dr. Anant R.
Subjects: Engineering, Civil
Keywords: structural dynamics; subcomponent analysis; structures; engineering
More Like This
6.
ARURKAR, TEJAS PRAKASH.
ACCELERATED CONSTRUCTION DECISION MAKING PROCESS.
Degree: MS, Engineering : Civil Engineering, 2006, University of Cincinnati
► The National Bridge Inventory shows that more than 480,000 bridges that serve…
(more)
▼ The National Bridge Inventory shows that more than 480,000 bridges that serve the U.S highways are of a median age of more than 42 years and a design life of 50 years; out of which, approximately 14 and 16 percent of the bridge inventory falls into the functional and structural deficient categories, respectively. In a mature infrastructure system, upgrade, repair, or replacement requires either restriction or closure of those parts of the system. Traffic disruption during maintenance and construction activities frequently results in disruptions to local economies and communities; and raises issues of safety and congestion. The use of traditional technologies and techniques for infrastructure rehabilitation are not effective enough to mitigate these disruptive effects of rehabilitation work. A systems approach to accelerating infrastructure construction is required to mitigate the impact of the extensive rehabilitation activities that are likely to take place in immediate future. The decision making system proposed in this report uses Analytical Hierarchy Process and provides the decision maker with a tool to quantify the qualitative trade-offs between various objectives to extract a single set of weights which reflect the level of importance of each of the factors in the overall decision making process. This system will thus provide the decision makers an excellent and transparent tool to make decisions regarding choosing an optimal holistic strategy for decision making.
Advisors/Committee Members: SALEM, Dr. OSSAMA.
Keywords: Acceleration; Pre-fabrication; Analytical Hierarchy Process
More Like This
7.
Barber, Matthew Gabriel.
Trends and Observations from Steel Stringer Bridge Model Calibrations.
Degree: MS, Engineering : Civil Engineering, 2008, University of Cincinnati
► To address the costs associated with bridge health monitoring, especially those directly…
(more)
▼ To address the costs associated with bridge health monitoring, especially those directly related to bridge condition assessment, the Ohio Department of Transportation contracted the University of Cincinnati Infrastructure Institute (UCII) to develop and test more efficient means of diagnosing and monitoring their bridges. UCII has developed a bridge condition assessment scheme which calibrates finite element (FE) models of a bridge structure based on the results of diagnostic field tests of the bridge in the form of vibrational mode testing, in some cases combined with truck load testing, in order to determine a load rating for the bridge. UCII researchers have designed an automated calibration method for these FE models. Most of research outlined in this thesis was performed in parallel with the development of the automated calibration method and served as an independent check of both the manual and automated calibration techniques. This thesis will show that, in general, the automated calibration process is a very efficient means of generating accurate FE representation of the bridges, and will suggest some potential areas of further refinement. In addition, the final chapter of this thesis will explore some issues related to the health monitoring of cable-stayed bridges, in particular the potential for interaction between deck and stay cable vibrations. Experimental data suggests that at certain frequencies, the bridge superstructure interacts strongly with individual cables. The chapter will describe a method of using FE models of the bridge and of the cables to predict bridge locations and cables likely to experience such interactions and suggest areas of potential further study regarding this phenomenon.
Advisors/Committee Members: Swanson, James.
Subjects: Civil engineering
Keywords: Modal analysis; Condition assessments; Finite element method; Objective functions; Dynamic Characteristics; Bridges; cable stay, cable vibration
More Like This
8.
BASU, BIKRAMADITYA.
ACCELERATED CONSTRUCTION AND REHABILITATION OF BRIDGES.
Degree: MS, Engineering : Civil Engineering, 2005, University of Cincinnati
► The growing traffic demands and an aging transportation network necessitate highway construction…
(more)
▼ The growing traffic demands and an aging transportation network necessitate highway construction to initiate and intensify efforts to accelerate repair and rehabilitation. Statistics show that vehicle miles have grown by 80 % between 1982 -2000 while the lane miles increased by only 3.8% during the same period. Any effort to close or restrict the highway for repair and rehabilitation work leads to unsafe conditions and major traffic delays. Extensive research has been conducted in various aspects of accelerated construction. Surveys have been conducted to identify factors for the success of different innovative contractual agreements. The contracts that were looked at for this work were design build, incentive/disincentive, A+B, warranty and Lane Rental. Research on accelerated construction has focused on the overall aspect of implementation of such concepts. This thesis however deals exclusively with the execution of the accelerated construction initiative by the Ohio Department of Transportation. Three bridges constructed under the initiative were chosen for study and research. The construction of the bridges, the ones in Guernsey, Clinton and Montgomery counties were observed by visiting the construction site, attending the pre and post construction meeting. These bridges used prefabricated post tensioned bridge decks. Data and information collected at the site and by interaction with different people associated in different capacity through the construction process was put together. The bridges in Clinton and Montgomery counties were compared because of the intrinsic similarity with the projects. Both were constructed using similar techniques and by the same contractor. One was a success and other not. The comparison revealed that small changes in the construction and planning were reflected in a substantial difference in project success. The conclusions and recommendations were based on the experience and understanding of the accelerated construction initiative. It showed that some of the areas that need to be worked on and improved upon for the project success are planning, changing of the existing mindset and other administrative issues and not technical aspects.
Advisors/Committee Members: SALEM, OSSAMA M.
Subjects: Engineering, Civil
Keywords: Bridges; Construction; Accelerated bridge construction; Innovative bridge construction; ODOT's Strategic Innitiative
More Like This
9.
BHATIA, AKASH.
A MODIFIED WIRELESS TOKEN RING PROTOCOL TO PREVENT DATA COLLISON IN WIRELESS TRAFFIC SENSORS.
Degree: MS, Engineering : Civil Engineering, 2006, University of Cincinnati
► Intelligent Transportation Systems, or ITS, is about using technology to solve transportation…
(more)
▼ Intelligent Transportation Systems, or ITS, is about using technology to solve transportation engineering problems. There is a major push by the Departments of Transportation to use wireless sensors all over the highways to provide accurate traffic information in real-time. Wireless Token Ring Protocol (WTRP), a wireless protocol based loosely on IEEE 802.4 [8] Token Bus Protocol, is an excellent Medium Access Control layer level protocol to prevent data collision in this wireless sensor network on the freeways. The distances between wireless sensors on the freeway were calculated, based on sensor frequency, sensitivity of the receiver and the transmitters, using the Free Space Path Loss Equation. Based on these calculations, it was found that Wireless Token Ring Protocol could fail, as the distances between the sensors was quite large and the data packets got lost, when being transmitted from the last sensor back to the first sensor. The Wireless Token Ring Protocol was modified such that instead of being uni-directional, transmitting data in one direction only; it became bi-directional, transmitting data in both directions. As such, during simulation, it was found that, the performance of the Modified Wireless Token Ring Protocol was better than that of Wireless Token Ring Protocol. The number of data packets that were lost in transmission or corrupted using Modified Wireless Token Ring Protocol was drastically less than that using Wireless Token Ring Protocol, over the same node positions. Hence, the Modified Wireless Token Ring Protocol is more effective than the Wireless Token Ring Protocol to prevent data collision and corruption on the field.
Advisors/Committee Members: Pant, Dr. Prahlad.
Subjects: Engineering, Civil
Keywords: Wireless Token Ring Protocol; Modified Wireless Token Ring Protocol; Wireless Sensors; ITS
More Like This
10.
BHIDE, ASHWINI M.
ANALYSIS OF ACCIDENTS AND INJURIES OF CONSTRUCTION EQUIPMENT OPERATORS.
Degree: MS, Engineering : Civil Engineering, 2006, University of Cincinnati
► Background-Safety continues to be one of the toughest challenges of the construction…
(more)
▼ Background-Safety continues to be one of the toughest challenges of the construction industry. The construction equipment operators referred here as heavy equipment operators are the class that operates a variety of heavy construction equipment. They perform diverse tasks and hence have the potential to be exposed to different types of injuries. Objective - To analyze the previous occurrences of accidents recorded by OSHA and verify the causation factors by means of a field study. The second objective is to check if the observed group is ergonomically safe. Method - OSHA has maintained a systematic record of accidents of equipment operators in the IMIS database (Integrated Management Information Systems) in the form of short summaries. The accident summaries are compiled and graphs are plotted to establish specific patterns in the occurrences of accidents. A group of construction equipment operators was observed on a construction site with the help of a checklist and Rapid Upper Limb Assessment (RULA) template to identify the accident causing practices followed and check if the amount of physical load imposed is within allowable range as stated by RULA tables. Results - The analysis showed that more than 50% accidents are a result of human error. The other causation factors observed were environmental interference, equipment breakdown and failure to comply with safety standards by the employer. The ergonomic evaluation showed that the group requires further investigation and immediate modifications in the working conditions. Conclusions -Intensive employee training, regular safety feedback and mandatory use of Personal Protective Equipment (PPE) are recommended to improve the safety of construction equipment operators. Modifications in the operator’s seat are recommended to reduce the threat of excessive physical loads.
Advisors/Committee Members: Salem, Dr. Ossama.
Subjects: Engineering, Civil
Keywords: Human Error, PPE, IMIS Database, Armand Wrist Score, Neck,Trunk and Leg Score
More Like This
11.
BOLDUC, MATTHEW W.
USE OF CARBON FIBER REINFORCED POLYMER PLATES FOR REPAIR OR RETROFIT OF PRESTRESSED AND REINFORCED CONCRETE GIRDERS.
Degree: MS, Engineering : Civil Engineering, 2003, University of Cincinnati
► Viable retrofit schemes are necessary to delay or offset replacement of deteriorating…
(more)
▼ Viable retrofit schemes are necessary to delay or offset replacement of deteriorating concrete bridge members. Carbon fiber reinforced polymer (CFRP) pultruded plates can be especially effective when retrofitting bridge members where stiffness, fatigue resistance, ease of installation, and weathering characteristics are a concern. The research reported in Chapter 1 was undertaken to examine the influence of fatigue loading, prior cracking, and patch materials on flexural performance of reinforced concrete members retrofitted with externally bonded CFRP plates. Moreover, experimental data from the six reinforced concrete beams tested as part of this research are expected to further evaluate available design equations for external retrofitting of reinforced concrete structures. The test results do not suggest a significant effect of fatigue loads; show that existing cracks do not significantly impact the strength of retrofitted members; and indicate that patch materials can reduce the available bond strength, and require additional surface preparation.The research reported in Chapter 2 presents a novel design approach utilizing externally bonded CFRP plates developed in an attempt to overcome construction errors in a member removed from an adjacent box girder bridge. The design methodology was evaluated based on data from testing of a retrofitted girder along with previous tests on as-is girders. Test data suggest appreciable improvements in terms of load carrying capacity and stiffness of the retrofitted girder. The relatively simple retrofit plan developed could have been used to delay replacement of the deficient girders.The research reported in Chapter 3 is aimed at filling some of the gaps in the available test data through retrofitting and testing of a 18.3 m (60 ft) prestressed box girder retrofitted with CFRP composite plates with mechanical anchors. Prior research on the use of CFRPs for retrofitting of existing structures has predominantly focused on mildly reinforced concrete members, and application to prestressed members is rather limited. Moreover, data regarding performance of mechanical anchors for enhancing bond characteristics of CFRP composites are scant. After a description of the design procedure, the test data are used to evaluate the design method, current design recommendations, and performance of mechanical anchors.
Advisors/Committee Members: Shahrooz, Dr. Bahram.
Subjects: Engineering, Civil
Keywords: CFRP Plate; use of CFRP for retrofit of concrete beams; flexural strengthening of reinforced concrete beams; use of CFRP plalte to repair a construction error; evaluation of current CFRP design methods
More Like This
12.
Bower, Owen J.
Analytical Investigation into the Effect of Axial Restraint on the Stiffness and Ductility of Diagonally Reinforced Concrete Coupling Beams.
Degree: MS, Engineering : Civil Engineering, 2008, University of Cincinnati
► The effects of axial restraint on the stiffness and ductility of diagonally…
(more)
▼ The effects of axial restraint on the stiffness and ductility of diagonally reinforced concrete coupling beams are investigated analytically through the use of finite element analysis. To provide accurate result without undue computational expense, a mesh sensitivity study is performed to determine the optimal mesh of the analysis. To validate the modeling technique, an analysis was performed reproducing experimental testing performed at the University of Cincinnati with good agreement between the two. An analysis was performed reproducing the experimental testing performed by Dr. Fortney at the University of Cincinnati. Finally, non-linear analysis of a prototype building utilizing the hysteretic response obtained from the finite element analysis for each case of axial restraint was performed. External axial restraint in diagonally reinforced concrete coupling beams is shown to increase the initial stiffness of the coupled core wall lateral force resisting system, as well as improve the post-peak stiffness and energy dissipation.
Advisors/Committee Members: Rassati, Gian.
Subjects: Civil engineering; Engineering
Keywords: Concrete; Shear Walls; Core Walls; Diagonally Reinforced Concrete Coupling Beam; Finite Element Analysis; Lateral Force Resisting System
More Like This
13.
BOY, SERPIL.
RETROFIT OF EXISTING REINFORCED CONCRETE BRIDGES WITH FIBER REINFORCED POLYMER COMPOSITES.
Degree: MS, Engineering : Civil Engineering, 2004, University of Cincinnati
► Fiber-Reinforced Polymer (FRP) plates and fabrics have emerged as viable systems for…
(more)
▼ Fiber-Reinforced Polymer (FRP) plates and fabrics have emerged as viable systems for retrofitting of existing reinforced concrete members with insufficient capacity. The results from previous research, conducted predominately on newly cast laboratory specimens, have been used to develop design guidelines. Detailed testing and evaluation of aged members retrofitted with FRP systems are very limited. This research is conducted to fill this gap. A 45-year old, three-span reinforced concrete slab bridge with insufficient capacity was retrofitted with 76.2 and 127-mm wide CFRP plates, 102-mm wide bonded CFRP plates with mechanical anchors at the ends, and bonded CFRP fabrics. Using four systems in one bridge provided an opportunity to evaluate field installation issues, and long-term performance of each system under identical traffic and environmental conditions. Through controlled truckload tests, the response of the bridge before retrofitting, shortly after retrofitting, and after one year of service was measured. The FRP system's stiffness was small in comparison to the stiffness of the bridge deck, therefore the measured deflections did not noticeably change after retrofitting. The measured strains suggest participation of the FRP systems, and more importantly the strength of the retrofitted bridge was increased. Detailed three-dimensional finite element models of the original and retrofitted bridge was developed and calibrated based on the measured deflections. Those models were used to calculate the rating factors and the corresponding load limits, which increased by 22% after retrofitting. In view of the increased capacity and performance of the bridge, load limits were removed and normal traffic was resumed.
Advisors/Committee Members: Shahrooz, Dr. Bahram M.
Keywords: Fiber Reinforced Polymer Composites; FRP; Retrofitting; Reinforced Concrete; Bridge; Installation; Design; Rating Factor; Load Rating; Moving Load Analysis; Normalization; ACI-440; AASHTO
More Like This
14.
BRODOWSKI, DAVID MICHAEL.
APPLICATION OF STEEL FIBER REINFORCED CONCRETE TO BURIED STRUCTURES.
Degree: MS, Engineering : Civil Engineering, 2005, University of Cincinnati
► Attributes associated with the addition of steel fibers may have significant effects…
(more)
▼ Attributes associated with the addition of steel fibers may have significant effects for the unique structural mechanism of large buried concrete structures such as culverts and bridges. CANDE, software developed under the sponsorship of FHWA in 1976, is recognized as the primary design and analysis tool for buried structures in the United States. Although CANDE models the behavior of reinforced concrete, it does not currently include an option for modeling steel fiber reinforced concrete (SFRC). The reported research focuses on the development of a new material type for CANDE that includes the effects of steel fibers in the concrete. An experimental and analytical approach was used to modify the CANDE finite element program and test the accuracy of the model. The research outcome is new input options to model the behavior of SFRC in the CANDE program needed to accurately predict the structural capabilities of SFRC buried structures.
Advisors/Committee Members: Shahrooz, Bahram.
Subjects: Engineering, Civil
Keywords: Steel fibers; Concrete
More Like This
15.
Cannady, Kristina M.
Effect of Larger Sized Coarse Aggregates and Microsilica on Environmental Properties of Portland Cement Concrete Pavements and Structures.
Degree: MS, Engineering : Civil Engineering, 2009, University of Cincinnati
► This project examines whether the addition of microsilica or the use of…
(more)
▼ This project examines whether the addition of microsilica or the use of aggregates with maximum size above 1.5 in., in concrete mixes prepared by the Ohio Department of Transportation (ODOT) for bridge decks and highway pavements, can have adverse effects on the durability properties of such structures. The behavior of several series of concrete specimens has been monitored over a period exceeding a year, and measurements of shrinkage, creep, abrasion, rapid chloride permeability, and freeze/thaw resistance have been recorded. Such data are evaluated to determine if altering the standard ODOT concrete mix design on either end of the gradation spectrum can indeed lower the cement content and increase its cost effectiveness and efficiency. It was found that different coarse aggregate gradations did not impact significantly the environmental properties of concrete examined. Variability issues related to the testing protocols themselves confounded the differences observed. These results indicate that larger sized coarse aggregates can be used for pavements and highway structures without significantly compromising the environmental properties of the concrete, and afford concrete producers more flexibility in creating cost-effective and cement-efficient mixes. It was found earlier in State Job No. 14800(0) that the compressive and flexural strengths of abused microsilica did not differ much from that of densified microsilica. This conclusion is brought into question, at least in the case of abused microsilica, by the rapid chloride permeability results obtained. Nonetheless, all values obtained are within the limits termed as low or moderate by the prevailing specifications.
Advisors/Committee Members: Ioannides, Anastasios M.
Subjects: Civil engineering
Keywords: aggregates; microsilica; concrete
More Like This
16.
DABKE, SHILPA SHRIKRISHNA.
JOB SATISFACTION OF WOMEN IN CONSTRUCTION TRADES.
Degree: MS, Engineering : Civil Engineering, 2005, University of Cincinnati
► Women face unique challenges to work and establish themselves in non traditional…
(more)
▼ Women face unique challenges to work and establish themselves in non traditional occupations such as construction trades. Existing research on women in construction focuses on engineers and entrepreneurs, yet little to no attention has been given to women in trades. Thus, the aim of this research is to review literature on tradeswomen, and to conduct a localized study to determine if demographic variables affect satisfaction with work, pay, opportunities, supervision, and people on the job for tradeswomen. These variables include age, education, number of dependents, number of trade years, duration of work, and frequency of work outside of the local area. Thirty-nine tradeswomen from the Cincinnati area were surveyed to assess their satisfaction or dissatisfaction with construction work. Currently, literature review indicates that research on tradeswomen is limited and largely restricted to identifying measures that can attract and retain women in construction trades. Studies on motivation and job satisfaction of construction workers neither identify nor compare perceptions of tradeswomen about their work. Results of this exploratory study showed that pay, benefits, and job security are most important to women in their occupation. Although tradeswomen appear to be satisfied with the nature of work in construction trades, this is not the case in terms of pay, benefits, and job security. Demographic variables did not affect the level of job satisfaction for women in construction trades. Research on tradeswomen is essential and important as the industry tries to change its image, encourage diversity in order to mitigate labor shortage.
Advisors/Committee Members: Salem, Ossama.
Subjects: Engineering, Civil
Keywords: Tradeswomen, job satisfaction, women in trades, work satisfaction
More Like This
17.
Dass, Praveen Kumar.
Evaluation of a Multi-linear Stiffness Model for T-Stub Connection Under Varying Fastener Pretension Levels.
Degree: MS, Engineering : Civil Engineering, 2006, University of Cincinnati
► The research focusses on determining important stiffness parameters of T-Stub Bolted Connection…
(more)
▼ The research focusses on determining important stiffness parameters of T-Stub Bolted Connection under varying pretension levels in fasteners. The parameters obtained through regression analysis as part of the research enables the Swanson’s Mathematical model to predict P - Δ curve more accurately.
Advisors/Committee Members: Swanson, Dr. James A.
Subjects: Engineering, Civil
Keywords: Swanson's Model, Swanson’s P - Δ Curve
More Like This
18.
DAYAL, NISHANT.
CONSOLIDATION ANALYSES OF GREATER CINCINNATI SOILS CINCINNATI, OHIO.
Degree: MS, Engineering : Civil Engineering, 2006, University of Cincinnati
► The compression analysis of argillaceous material under a proposed superstructure is one…
(more)
▼ The compression analysis of argillaceous material under a proposed superstructure is one of the primary tasks required of a geotechnical engineer. The accuracy of such an analysis is dubious in the absence of proper geotechnical investigation. A proper geotechnical investigation involves site reconnaissance, determination of subsurface conditions, in situ and laboratory tests, and settlement monitoring, if required. This research fulfills several objectives, i.e. analyses of primary consolidation, proposes new correlations, and compares observed and predicted values of settlement. The current paper introduces several new correlations between the compression index and soil parameters such as natural water content, initial void ratio, liquid limit, plasticity index, specific gravity of soil solids, and dry unit weight for the soils of Greater Cincinnati based on regression analysis. Previously available correlations are also analyzed. Most of the new equations obtained show statistical improvement over their predecessors. The data used to obtain these new correlations were provided by local consulting firms including H. C. Nutting Company and Thelen Associates, as well as the Ohio Department of Transportation. Several case studies are presented which compare predicted settlements (by local engineers) and measured settlements due to consolidation of clays. This work then validates the new equations. These case studies are based on project reports provided by H. C. Nutting Company and are intended to help local engineers in predicting consolidation settlements more accurately.
Advisors/Committee Members: Bowers, Dr. Mark T.
Subjects: Engineering, Civil
Keywords: Primary Consolidation; Settlement; Settlement Monitoring; Initial Void Ratio; Compression Index; Soils in Cincinnati; Clays
More Like This
19.
DEASON, JEREMY THOMAS.
SEISMIC DESIGN OF CONNECTIONS BETWEEN STEEL OUTRIGGER BEAMS AND REINFORCED CONCRETE WALLS.
Degree: MS, Engineering : Civil Engineering, 2002, University of Cincinnati
► Cyclic response of shear connections between steel outrigger beams and reinforced concrete…
(more)
▼ Cyclic response of shear connections between steel outrigger beams and reinforced concrete core walls is presented in this paper. The connections investigated in this paper consisted of a shear tab welded onto a plate that was connected to the core walls through multiple headed studs. The experimental data from six specimens point to a capacity that is larger than the design value. The mode of failure was through pullout of the embedded plate, or fracture of the weld between the studs and the plate. Such brittle modes of failure need to be avoided through proper design. A capacity design method based on dissipating the input energy through yielding of the shear tab was developed. This approach requires a good understanding of the expected capacity of headed studs under combined gravity shear and cyclic axial load (tension and compression). A model was developed and verified against test results from six specimens. A seventh specimen whose design was based on the proposed design methodology was then tested. Based on the performance of this specimen, the proposed design method is recommended for the design of outrigger beam-wall connections.
Advisors/Committee Members: Shahrooz, Dr. Bahram.
Subjects: Engineering, Civil
Keywords: connections; SEISMIC; design concrete core; outrigger beam
More Like This
20.
DESHINI, AMARENDRANATH.
FINENESS OF DENSIFIED MICROSILICA AND DISPERSION IN CONCRETE MIXES.
Degree: MS, Engineering : Civil Engineering, 2007, University of Cincinnati
► This study explores the effect of densification of microsilica on the mechanical…
(more)
▼ This study explores the effect of densification of microsilica on the mechanical and other engineering properties of concrete used on Ohio Department of Transportation (ODOT) projects. American Society for Testing and Materials (ASTM) C 1240 requires wet-sieved microsilica to pass a No. 325 sieve with no more than 10% retained. Densified microsilica samples submitted to ODOT sometimes do not meet this specification, since the sieving process may not be able to break the bonds formed due to densification. During this study, No. 325 sieve tests on three microsilica types (undensified, densified, and abused by prolonged exposure to moisture) were performed at the ODOT laboratory, but none of the materials tested were found to conform to the ASTM fineness specification. This calls into question the application of this procedure to assessing the suitability of densified microsilica for use in concrete. In contrast, the compressive and flexural strengths of concretes mixed with each of the three microsilica types exceeded those envisaged by ODOT Item 499.03 Concrete-General: Proportioning. As expected, undensified microsilica concrete yielded higher values than its densified and abused microsilica counterparts at all ages, but this advantage was rather limited. This was true for both natural and crushed coarse aggregate mixes. With very few exceptions attributable to material and testing variability, trends observed with regard to the effects of microsilica and coarse aggregate types, age and specimen size on the development of strength were also as anticipated. Therefore, it is concluded that densified microsilica can be used on ODOT projects for the construction of pavements and bridges.
Advisors/Committee Members: IOANNIDES, Dr. ANASTASIOS.
Subjects: Engineering, Civil
Keywords: Microsilica, Silica fume
More Like This
21.
Deshpande, Abhijeet Sudhakar.
Best Practices for the Management of Design in Fast Track Industrial Projects.
Degree: PhD, Engineering : Civil Engineering, 2009, University of Cincinnati
► The fast track project delivery strategy is designed to leverage the ability…
(more)
▼ The fast track project delivery strategy is designed to leverage the ability to execute design, procurement and construction phases simultaneously to substantially reduce the project schedule. The design phase assumes increased importance in fast track projects because design and construction are executed almost simultaneously with very little or no lag between design and construction. The design of industrial projects involves the design of complex and interconnected systems in which design teams from various disciplines need to continuously interact and use data from each other to ensure accurate and safe design. The performance of the design phase is dependent on smooth and timely flow of accurate information from a variety of stakeholders from different organizations that come together to execute the project. The successful execution of design process in fast track projects is especially challenging because the compressed schedule interferes with the inherently iterative nature of design, resulting in sub-optimal design. The typical lack of time for pre-project planning in fast track projects results in inadequate development of project and design scope, causing costly changes during project execution which result in project cost overruns and schedule slippages and deterioration of quality of the final product. The fast track project delivery strategy is being used ever more aggressively in industrial projects to reduce the time to the market, making the study of best practices for management of design in fast track industrial projects more cogent.The conclusions presented in this research are based on a comprehensive review of research literature, quantitative and qualitative analysis of the performance of design phase in thirty one fast track industrial projects, expert opinion and case studies. The quantitative analysis of performance of design involved the identification of correlation between the cost and schedule performance of design phase in fast track projects and use of practices identified from the review of literature. In this research, it was hypothesized that there is a correlation between the use of practices such as pre-project planning, constructability, alignment, change management, design effectiveness, partnering, design for maintainability, team building, design for safety, modularization and preassembly, and the performance of design in fast track projects. The quantitative analysis revealed a statistically significant correlation between the schedule performance of design phase in fast track projects and pre-project planning, alignment, constructability, and change management. The results of quantitative analysis are supported by the qualitative analysis of information, expert opinion and case studies. In addition to these practices, other innovative techniques and tools such as lean design, and the use of intelligent 3D models were found to improve the performance of design in fast track projects. These have been discussed in detail with case studies.
Advisors/Committee Members: Salem, Ossama.
Subjects: Civil engineering
Keywords: Fast Track Construction; Industrial Construction; Design Management
More Like This
22.
DESHPANDE, NITIN PRAKASH.
SPATIAL DISTRIBUTION AND CHARACTERISTICS OF FATAL and INJURY CRASHES AT WORK ZONES IN OHIO'S INTERSTATES.
Degree: MS, Engineering : Civil Engineering, 2005, University of Cincinnati
► This study identifies the spatial distribution and characteristics of fatal and injury…
(more)
▼ This study identifies the spatial distribution and characteristics of fatal and injury crashes at different work zone locations on interstate freeways in Ohio based on the data provided for the last three years. Work zone accident computer data file obtained from the Ohio Department of Transportation (ODOT) and the Ohio Department of Public Safety (ODPS) provided necessary information for the analysis. A total of 1448 accidents that occurred on Ohio’s interstate freeways from 2001 through 2003 were analyzed. A clear understanding of fatal and injury crash characteristics, distribution of work zone fatal and injury crashes within a work zone, and analysis of prevailing work-zone conditions helped to identify the factors that contribute to unsafe conditions within work zones at interstate locations. Proportionality test results indicate that there is a significant difference in the proportion of fatal and injury crashes at different locations within a work zone. The activity area is the predominant location of work zone crashes and safety efforts must be concentrated on this area to improve the work zone safety. Predominance of rear-end crashes at all locations within a work zone indicates a high speed variance. Any countermeasures to reduce the speed variance within a work zone may improve the work zone safety.
Advisors/Committee Members: Salem, Dr. Ossama M.
Keywords: Work zone safety; Crashes; Fatal; Injury accidents; Traffic safety; Rear-end crashes; Proportionality tests
More Like This
23.
DIMMERLING, AMY JO.
CONNECTION BETWEEN SIMPLE SPAN PRECAST CONCRETE GIRDERS MADE CONTINUOUS-EMBEDDED CONNECTIONS.
Degree: MS, Engineering : Civil Engineering, 2002, University of Cincinnati
► Precast prestressed concrete girders have been used in bridge construction for several…
(more)
▼ Precast prestressed concrete girders have been used in bridge construction for several years in the United States. In general, these types of bridges have performed well in service conditions. Although the connections over the supports provide sufficient continuity for dead loads, which cause negative moments, there has been some concern about the ability of the connections to provide continuity for the positive moments caused by live loads. Cracking has been observed at the bottom of the diaphragm at the connection and this raises concern about the connection's performance. The National Cooperative Highway Research Program developed Project 12-53 to study the effectiveness of these connections. The focus of this research deals with the experimental testing part of project 12-53. Six specimens that represent portions of full-size bridges were tested under monotonic and cyclic loads to evaluate their performance after cracking occurs at the bottom of the diaphragm. Each connection was fatigued until the connection was considered to have failed. The bent strand and bent bar embedded connections performed well under service moments. Under negative moment all of the specimens performed well. Even after failure of the specimens they each were able to resist the negative moment. This was due to the bearing of the diaphragm against the beams. The crack closes and at this point there is no difference between the specimens. Under positive moment the embedded specimens were stiffer and the failure was more gradual than that of the not embedded specimens. The embedment adds to the stiffness of the specimens. The engagement of the diaphragm in the embedded specimens helps to prolong the failure. The warning signs of failure are more prominent in the embedded specimens. The bent bar specimens are stiffer than the bent strand but the failure occurs more rapidly. After all six of the short-length specimens are tested, full-size specimens will be tested. At that point, results from all testing will be compared and discussed providing conclusions about the behavior of positive moment connections. Also, recommendations are expected as to the design and construction of positive moment connections in precast/prestressed bridge girders made continuous.
Advisors/Committee Members: Miller, Dr. Richard.
Subjects: Engineering, Civil
Keywords: continuity; precast prestressed; concrete connections
More Like This
24.
DONG, XUHUA.
TRAFFIC FORCES AND TEMPERATURE EFFECTS ON SHEAR KEY CONNECTIONS FOR ADJACENT BOX GIRDER BRIDGE.
Degree: PhD, Engineering : Civil Engineering, 2002, University of Cincinnati
► Adjacent box girder bridges are widespread around the world. They have many…
(more)
▼ Adjacent box girder bridges are widespread around the world. They have many advantages such as ease of erection, excellent depth-to-span ratio and speeding up the construction, etc.. Usually these kind of bridges are built up by placing the box girders side by side, then pouring grout into an octangular shaped gap between the beams which is called "shear key". Finally the girders are pulled together by a series of lateral ties (post-tensioning forces may be applied). The focus of this research is the "shear key" leakage problem, since for the current "shear key" design, the cracking could be easily caused after "shear key" is formed. Those cracks can let salt laden water penetrate through the beam joints, then the load transfer between girders could be lost. That would affect the integrity and the strength of the whole bridge. The finite element method was applied in this analytical analysis. The finite element program, ANSYS, was first verified to be a valid tool by doing the analysis compared with an experimental test. Then in order to find out the best design for "shear key" connection, ANSYS was used to analyze five "shear key" variations: "Regular keyway", "Neutral-axis keyway", "full-depth keyway", "Regular hinge keyway" and "Neutral-axis hinge keyway". Two kinds of material, which are used in grouting shear keys, were involved in this analysis and they are non-shrink grout and hi-flow epoxy. Several load conditions were considered: HS-20 truck load, temperature effect and post-tensioning forces. The combinations of these separate load conditions were also being analyzed. Some analytical results were compared with some previous studies to check the consistency of the analytical results and field experimental data. According to the result of the analytical analyses, "full-depth keyway" was found to be the best option for shear key design, since it always had the lightest critical stress or cracking condition compared with other four variations. Non-shrink grout was shown to be a better choice than hi-flow epoxy when temperature issue could not be neglected, because the thermal expansion coefficient of hi-flow epoxy is too high. Post-tensioning forces are also recommended to be applied on the adjacent box girder bridges, because in this finite element analysis it was verified that post-tensioning effect could improve the anti-cracking capacity of shear key connections. So "full-depth keyway" approach with using non-shrink grout, combined with post-tensioning forces, is the proposed design method from this analytical analysis.
Advisors/Committee Members: Miller, Dr. Richard A.
Subjects: Engineering, Civil
Keywords: FINITE ELEMENT; PRESTRESS; REINFORCED CONCRETE
More Like This
25.
EDER, ERIC WILLIAM.
BEHAVIOR OF 50 YEAR OLD PRESTRESSED CONCRETE BRIDGE WITH FIBER REINFORCED POLYMER DECK REPLACEMENT.
Degree: MS, Engineering : Civil Engineering, 2003, University of Cincinnati
► Bridges B-0071, and B-0171 in Hamilton County, Ohio have been in service…
(more)
▼ Bridges B-0071, and B-0171 in Hamilton County, Ohio have been in service for about fifty years. They are short span bridges with prestressed concrete girders. Until late 2001, they had conventional reinforced concrete decks. On November third of that year the ribbon was cut to reopen the bridges, now with Fiber Reinforced Polymer Decks. One of the bridges also had the girders replaced. These are the only bridges in existence that have FRP decking on concrete girders. The Hamilton County Engineers Office contracted with the Civil Engineering Department at the University of Cincinnati to perform research on these bridges. Information gained from this research will seek to confirm the safety of the new technology, approve construction and design techniques with reference to the FRP deck, and determine overall performance of the bridge to provided understanding of the system. The 50-year-old prestressed concrete girders were subjected to destructive load testing. The girders showed little loss of strength or stiffness from aging. The information on the performance of the girders was used in the analysis of the bridge system. Two of the bridges were subjected to nondestructive load testing. A three-dimensional finite element model was then created to replicate the performance of the bridges. Data from the bridge tests provided enough information to create an accurate model of the bridge girders, but not the deck. Using the finite element model, a Load Rating was performed. The bridges were found to be sufficiently strong to resist the loads that may be applied to them. The deck showed no signs of separation from the concrete girders as was previously suspected. The bridge system acted as a fixed end beam because of the semi-integral end abutments for the range of loads tested. The deck was not adding any strength tot the girders through composite action. The load transfer from one girder to another was not provided by the deck as was assumed in the design process, but by the concrete diaphragms used for lateral stability. Further testing will be needed to understand the deck performance better so that a full bridge analysis may be performed.
Advisors/Committee Members: Swanson, Dr. James.
Subjects: Engineering, Civil
Keywords: prestressed concrete; fiber reinforced polymer deck; load rating; bridges; non-destructive testing
More Like This
26.
FORTNEY, PATRICK JOSEPH.
THE NEXT GENERATION OF COUPLING BEAMS.
Degree: PhD, Engineering : Civil Engineering, 2005, University of Cincinnati
► A collection of experimental, parametric, and analytical studies was carried out to…
(more)
▼ A collection of experimental, parametric, and analytical studies was carried out to further the understanding of the behavior and constructability of coupled core wall (CCW) systems. Issues related to the design of wall piers in CCW systems and the beams used to couple the wall piers, structural response of the overall system, and construction difficulties arising from reinforcing steel congestion were explored. The research presented in this document focuses on a design approach of coupled core wall systems which concentrates on minimizing steel congestion while maintaining satisfactory structural behavior. To investigate the overall structural behavior of coupled core wall systems with wall piers and coupling beams designed based on the recommendations of this research, nonlinear time-history analyses were performed on two prototype structures. Both structures had the same plan dimensions, number of stories, slab thickness, wall thickness, and floor-to-floor heights. The first structure was designed using a steel coupling beam, and the second was designed using a diagonally-reinforced concrete coupling beam. The need for special boundary elements in the wall piers was based on maximum concrete compressive strains at design loads. Properties of the coupling beams used in the analyses of the two structures were based on measured behavior obtained during the experimental phase of the research.
Advisors/Committee Members: Shahrooz, Dr. Bahram M.
Subjects: Engineering, Civil
Keywords: Coupled Core Wall Systems; Coupling Beams; Wall Piers; Special Boundary Elements; Shear Plate coupling Beam; Fuse steel Coupling Beam
More Like This
27.
Gade, Satya Sai Sravan Kumar.
Preliminary Evaluation Of Post-Production Heat Treating Of HPS 70W Steel.
Degree: MS, Engineering : Civil Engineering, 2008, University of Cincinnati
► The cooperative research program launched by the Federal Highway Administration in cooperation…
(more)
▼ The cooperative research program launched by the Federal Highway Administration in cooperation with the U.S. Navy and the steel industry was a great success in bringing high performance steel technology to the bridge industry. The past decade has seen many developments as part of this research program, the first of them being the development of HPS-70W, a high performance steel material with yield strength of 70 ksi (483 MPa). Its high strength, better weldability, improved toughness, inherent weathering resistance and improved ease of fabrication has helped engineers and bridge owners to design and build bridges more efficiently. Significant material and cost savings have been reported in many of these bridge projects (Wright 1997). HPS-70W is the most widely used, researched and tested of the high performance steels to date. With the success of HPS-70W, an HPS version of 50 ksi (345 MPa) steel has been developed (Wilson 2003). Design specifications for bridges using these steels are being developed and continuously updated as research results are published. Hybrid girder design which incorporates the use of HPS-50W along with HPS-70W has been reported to be effective in using high performance steels for bridge construction. HPS-70W plates up to 4 in (102 mm) thick can be produced by quenching and tempering process (Q&T), but this process limits plate lengths to 50 ft (15 m). A new production technique called Thermal-Mechanical Controlled Processing (TMCP) has recently been developed that yields steel having similar properties (Lwin 2002). TMCP practices can be used to produce HPS-70W plates up to 2 in (51 mm) thick and to 125 ft (38 m) long. The present work concentrates on evaluating various post-production heat treating methods for application to HPS-70W. Methods such as heat curving, heat cambering and flame straightening are used during fabrication and repair of bridge members. There is a concern that these methods might have undesirable effects on the mechanical properties of HPS-70W. The present work focuses on evaluating the effect of these heat treating methods on the properties of HPS-70W, and determining the transition temperature, which is critical during the application of post-production heat treating methods. From the results obtained, it was concluded that post-production heat treating techniques with a limiting temperature of 1275 °F (691 °C) can be used on HPS-70W with no apparent effect on its tensile properties. A more refined approach is required to evaluate the effect on toughness properties of HPS-70W.
Advisors/Committee Members: Swanson, James.
Subjects: Civil engineering
Keywords: Heat Treating; HPS-70W
More Like This
28.
GANESH, PRAKASH.
TRANSVERSE CRACKING OF HIGH PERFORMANCE CONCRETE BRIDGE DECKS.
Degree: MS, Engineering : Civil Engineering, 2006, University of Cincinnati
► Cracking is a major problem with newly placed concrete decks. These decks…
(more)
▼ Cracking is a major problem with newly placed concrete decks. These decks tend to develop full depth, transverse cracks and partial depth longitudinal cracks within a few months of the concrete being placed. A literature review showed that several other states had experienced similar problems. A review of data from Ohio bridge decks showed weak correlations between deck cracking and slump, time of year when the deck was placed, shrinkage, chloride permeability and compressive strength, but there was no clear relationship between cracking and any of these properties. Data also suggested that using a coarse aggregate with an absorption > 1% may help mitigate deck cracking but will not always stop it. As part of this study, three bridge decks were instrumented. One was a standard class “S” concrete deck and the other two were high performance concrete. The class “S” deck showed only hairline cracking after 1 year, but transverse cracking occurred in the HPC decks. Instruments were placed in the decks to monitor strains. From the data, it appears that cracking is caused by several factors. High heat of hydration caused the plastic concrete to expand. When the concrete sets and cools, tensile stresses develop. Additional tensile stresses develop through drying shrinkage. Restraining the deck against normal thermal movement contributes to additional tensile stress. Autogeneous shrinkage, where high heats of hydration cause water evaporation during hydration, and plastic shrinkage may cause more tensile stress. Recommendations for mitigating cracking include using lower cement contents, adding pozzolans and retarders, using slightly higher water/cement ratios, using larger aggregates, taking steps to limit shrinkage and eliminating restraints.
Advisors/Committee Members: Miller, Dr. Richard.
Subjects: Engineering, Civil
Keywords: Cracking, Restraint, High Performance Concrete, Finite Element Model
More Like This
29.
GAO, XIAOJIANG.
STRENGTH DETERMINATION OF HEAVY CLIP-ANGLE CONNECTION COMPONENTS.
Degree: MS, Engineering : Civil Engineering, 2002, University of Cincinnati
► From the late 1970s through the early 1990s fully welded beam-column connections…
(more)
▼ From the late 1970s through the early 1990s fully welded beam-column connections were considered to be the connection of choice in moment resisting structural frames, especially in seismic regions. During the Northridge and Kobe earthquakes, however, fully welded connections suffered significant damage. Although improvements in welding methods and advancements in materials may help to improve the overall performance of welded connections, bolted connections provide an attractive alternative. The primary objective of the thesis is to provide recommendations for determination of the strength of clip angle connections. This objective were achieved by conducting an examination of the clip angle test data that was acquired during Subtask 7.03 of the SAC Research Project with regard to strength characteristics. The results of 10 component clip angle tests were presented and evaluated based on their strength characteristics. Several existing strength models are evaluated for accuracy and simple modifications were proposed. The examination included evaluations of current design procedures included in the AISC LRFD specification (1994), the Eurocode (1993), Chen, W. F. Model and Modified Kulak Model. The results are used to compare several existing strength models that govern the failure modes of including tension bolt fracture, mixed model failure and flange mechanism.
Advisors/Committee Members: Swanson, Dr. James A.
Subjects: Engineering, Civil
Keywords: strength determination; clip-angle; steel connection; semi-rigid connection; partially restrained connection
More Like This
30.
GEARA, TONY GEBRAEL.
Improved Models for User Cost Analysis.
Degree: MS, Engineering : Civil Engineering, 2008, University of Cincinnati
► The user costs include the costs borne by highway users such as…
(more)
▼ The user costs include the costs borne by highway users such as additional travel time costs, crash costs, costs of operating vehicles in work zone conditions, and environmental costs. The pavement type selection process currently used by Ohio Department of Transportation (ODOT) does not include user costs quantitatively. This thesis provides a comprehensive review of literature and tools used to calculate user costs. The results of a questionnaire survey on the role played by user costs in pavement type selection processes of various state and regional agencies in US and Canada are provided. Based on the findings from literature review and questionnaire survey, this thesis investigates and provides recommendations for including user delay costs quantitatively in Ohio DOT's pavement type selection process. Two case studies presented in this thesis illustrate the methods recommended in this thesis and their applicability to real life scenarios.
Advisors/Committee Members: Salem, Osama.
Subjects: Civil engineering
Keywords: Pavement Type Selection, User Costs, User Delay Costs, Vehicle Operating Costs
More Like This
[1] [2] [3] [4]
