Prestress Losses in Pretensioned High-strength Concrete Bridge Girders

Prestress Losses in Pretensioned High-strength Concrete Bridge Girders
Author: Maher K. Tadros
Publisher: Transportation Research Board
Total Pages: 73
Release: 2003
Genre: Technology & Engineering
ISBN: 030908766X
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"The HCM includes three printed volumes (Volumes 1-3) that can be purchased from the Transportation Research Board in print and electronic formats. Volume 4 is a free online resource that supports the rest of the manual. It includes: Supplemental chapters 25-38, providing additional details of the methodologies described in the Volume 1-3 chapters, example problems, and other resources; A technical reference library providing access to a significant portion of the research supporting HCM methods; Two applications guides demonstrating how the HCM can be applied to planning-level analysis and a variety of traffic operations applications; Interpretations, updates, and errata for the HCM (as they are developed);A discussion forum allowing HCM users to ask questions and collaborate on HCM-related matters; and Notifications of chapter updates, active discussions, and more via an optional e-mail notification feature."--Publisher.

Optimization of the Prestressing Force in Continuous Concrete Bridges

Optimization of the Prestressing Force in Continuous Concrete Bridges
Author: Eduardo Rene Raudales Valladares
Publisher:
Total Pages: 71
Release: 2016
Genre: Prestressed concrete bridges
ISBN:
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Most engineers may agree that an optimum design of a particular structure is a proposal that minimizes costs without compromising resistance, serviceability and aesthetics. Additionally to these conditions, the theory and application of the method that produces such an efficient design must be easy and fast to apply at the structural engineering offices. A considerable amount of studies have been conducted for the past four decades. Most researchers have used constraints and tried to minimize the cost of the structure by reducing the weight of it [8]. Although this approach may be true for steel structures, it is not accurate for composite structures such as reinforced and prestressed concrete. Maximizing the amount of reinforcing steel to minimize the weight of the overall structure can produce an increase of the cost if the price of steel is too high compared to concrete [8]. A better approach is to reduce the total cost of the structure instead of weight. However, some structures such as Prestressed Concrete AASHTO Girders have been standardized with the purpose of simplifying production, design and construction. Optimizing a bridge girder requires good judgment at an early stage of the design and some studies have provided guides for preliminary design that will generate a final economical solution [17] [18]. Therefore, no calculations or optimization procedure is required to select the appropriate Standard AASHTO Girder. This simplifies the optimization problem of a bridge girder to reducing the amount of prestressing and mild steel only. This study will address the problem of optimizing the prestressing force of a PC AASHTO girder by using linear programming and feasibility domain of working stresses. A computer program will be presented to apply the optimization technique effectively.

Shear Behavior and Design of High Strength Concrete Prestressed Bridge Girders

Shear Behavior and Design of High Strength Concrete Prestressed Bridge Girders
Author: Emad Leon Labib
Publisher:
Total Pages:
Release: 2012
Genre: Civil engineering
ISBN:
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A simple semi-empirical set of equations was developed at the University of Houston (UH) to predict the shear strength of PC I-girders with normal-strength concrete. The UH-developed equation is a function of concrete strength, web area, shear span to effective depth ratio, and percentage of transverse steel. This research intends to validate or modify the UH-developed equation for (1) high-strength concrete and (2) different sizes of PC girders and studying the possibility of premature failure due to local failure in end zone. Ten modified Tx28 PC girders, derived by scaling down an existing TxDOT cross section, were tested in this study for the first objective. The girders were divided into three groups (Groups A, C and F) based on the concrete strength. Each group of the PC girders was tested with different shear span to effective depth ratio. The validity of the proposed UH-developed equations was ascertained using the experimental results. It was found able to predict accurately the ultimate shear strength of PC girders with concrete strength up to 117 MPa (17,000 psi) with enough ductility. Six PC girders of Tx-series with three different sizes were tested for the second objective. The girders were divided into three groups (Groups D, E and G) based on the girder depth. The experimental results ensured the validity of the UH-developed equations for PC girders with different sizes. Also, the experimental data showed that the PC girders of the new Tx-series can reach the maximum shear capacity without a shear-bond failure. The results of testing the 10 modified Tx-28 girders were used to validate a finite element program developed at UH, Simulation of Concrete Structures (SCS), for PC girders with different concrete strength. Analytical results presented in this dissertation proved the validity of SCS to predict the behavior of PC girders with different concrete strength up to 117 MPa (17,000 psi).