Engineering Commons^™

Continuity Of Bridges Composed Of Simple-Span Precast Prestressed Concrete Girders Made Continuous, Libin Yin

Dissertations

Bridges composed of simple-span, precast, prestressed concrete girders made continuous via cast-in-place decks and diaphragms are continuous only for live loads and superimposed dead loads. The continuity diaphragms often crack due to time dependent effects in the girders. These cracks not only impair bridge ascetics and durability, but also reduce "degree of continuity". A related issue is that joint construction is time consuming and expensive due to reinforcement congestion. This dissertation presents a series of field tests, analytical studies, and laboratory experiments concerning the design and performance of this type of bridge.

Based on a survey of the state departments …

Design Considerations For The Construction And Operation Of Feed Milling Facilities. Part I: Planning, Structural, And Life Safety Considerations, Gregory D. Williams, Kurt A. Rosentrater

Kurt A. Rosentrater

Feed mills represent an important segment of our food production system, supplying the nutritional need for animals in our meat supply system. Agri-industrial facilities such as feed mills have a number of unique design requirements that are relatively unknown. The purpose of this paper is to summarize state of the art design procedures for feed milling facilities constructed in North America. To this end, in Part I of this series, planning, life safety, and structural design criteria for these facilities are examined and relevant theory is presented. Additional resources are cited for further study of concepts. This paper should be …

Design Considerations For The Construction And Operation Of Grain Elevator Facilities. Part I: Planning, Structural, And Life Safety Considerations, Gregory D. Williams, Kurt A. Rosentrater

Kurt A. Rosentrater

Grain elevators represent a major link our food production system. To date, information about the unique design requirements of these facilities has been limited. In an effort to summarize state of the art design procedures for grain elevator facilities constructed in North America, an overview of accepted standards and procedures has been assembled. With this paper engineers should become more familiar with specific design considerations for grain handling facilities and develop appropriate references to expand their knowledge base. Educators may find this paper useful too.

Comparison Of Water And Saltwater Movement In Mortar Based On A Semiempirical Electromagnetic Model, Shanup Peer, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

The presence of chloride ions in steel-reinforced structures leads to the corrosion of the reinforcement thus compromising the integrity and strength of the structure. Thus, it is of great interest to nondestructively detect and evaluate free chloride content in concrete. To this end, an investigation was initiated where two mortar cubes were soaked in distilled water and saltwater solutions, respectively. Their temporal microwave reflection properties were measured using open-ended rectangular waveguides on a daily basis for three cycles, each lasting 35 days. Subsequently, a semiempirical electromagnetic model was developed to simulate the reflection properties of the cubes. The outcome of …

Performance Of Self-Compacting Concrete, Mohamed Samir Rushdy

Archived Theses and Dissertations

Concrete compaction is one of the indispensable fundamentals of concrete manufacturing. However, thorough compaction cannot always be insured. This can be wholly or partially encountered in congested sections, out-of reach deep foundations and narrow or irregular precast components. On the other hand, typical vibrators were considered as contributor to health hazards to workers. Self-compacting concrete (SCC) is an emerging concrete where the cohesive yet flowable consistency of the concrete itself secures adequate placement with high level of homogeneity and little or no segregation. Such concrete is primarily achieved by incorporating admixtures that is referred to as viscosity modifying (VM) admixtures …

End Zone Reinforcement For Pretensioned Concrete Girders, Christopher Y. Tuan, Sherif A. Yehia, Nipon Jongpitaksseel, Maher K. Tadros

Civil Engineering Faculty Publications

In this study, a literature review was conducted to establish the background of current specifications and to evaluate the applicability of various theories and methods for design of end zone reinforcement. Analytical methods reviewed in this paper include finite element analysis, strut-and-tie modeling, and the Gergely-Sozen equivalent beam method. Previous experimental work combined with work conducted as part of this study was used to correlate between various theoretical and experimental results. This paper illustrates that no single theoretical method adequately represents the complex behavior at the end of a pretensioned concrete member. A general semi-empirical design procedure is proposed here. …

An Electromagnetic Model For Evaluating Temporal Water Content Distribution And Movement In Cyclically Soaked Mortar, Shanup Peer, K. E. Kurtis, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Evaluation of water distribution and its temporal movement in cement-based materials is important for assessing cement hydration, curing, and long-term performance. From a practical standpoint, it is also important to obtain this information nondestructively. Near-field microwave nondestructive evaluation methods have proven effective for evaluation of cement-based materials for their various mixture properties, including the detection of salt added to the mixing water and chloride ions entering these materials through exposure to salt water solutions. Electromagnetic modeling of the interaction of microwave signals with moist cement-based materials can provide the necessary insight to evaluate water content distribution and movement in these …

Evaluation Of Fire Resistance Of Plastering Applied To Reinforced Concrete, Engy M Samy Serag

Archived Theses and Dissertations

Concrete is one of the most resistant construction materials to heat and fire. It is known to retain heat for a relatively long time, thus limiting crack propagation from penetrating deeply. Furthermore, it can be repaired if exposed to fire for a limited time. However it loses its strength dramatically when exposed to elevated temperatures for long duration. With the increase in the use of concrete in structures, a demand arises to assess the fire resistance of concrete structural members and to develop means of improving the fire characteristics of these elements. One of the methods to increase the fire …

Recycled Concrete Properties And Feasibility, Mourad Nabil Shenouda

Archived Theses and Dissertations

As conventional good quality aggregates are becoming scarce in some zones in Egypt and many areas worldwide, and as environmental concerns are raised on dumping old and fresh concrete in landfills, recycled concrete has been receiving increased interest worldwide for its potential environmental, economic and technical merits. In fact, many countries have adopted such concrete in their codes and the majority of their old concrete is being recycled. An attempt is being made to trigger factors and means that enhance the economic feasibility of recycled concrete. The overall goal of this work is to pinpoint strength and deficiencies in this …

Interaction Between Micro-Cracking, Cracking, And Reduced Durability Of Concrete: Developing Methods For Considering Cumulative Damage In Life-Cycle Modeling, Zhifu Yang, W. Jason Weiss, J. Olek

JTRP Technical Reports

It is becoming increasingly popular to utilize numerical simulation models to predict the long-term performance of concrete pavements and structures. The majority of these models have been developed using laboratory test data that considers concrete in an uncracked state. While uncracked concrete exists as the best case scenario, frequent cracking occurs in real structures that could have a profound impact on life cycle performance. Cracks from several sources may accumulate and interact thereby accelerating the deterioration of concrete. For example, the distributed cracking caused by freeze/thaw damage can substantially increases the rate of water absorption and reduces the load carrying …