Investigation of Long-term Prestress Losses in Pretensioned High Performance Concrete Girders - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Investigation of Long-term Prestress Losses in Pretensioned High Performance Concrete Girders write by Thomas E. Cousins. This book was released on 2005. Investigation of Long-term Prestress Losses in Pretensioned High Performance Concrete Girders available in PDF, EPUB and Kindle. Effective determination of long-term prestress losses is important in the design of prestressed concrete bridges. Over-predicting prestress losses results in an overly conservative design for service load stresses, and under-predicting prestress losses, can result in cracking at service loads. Creep and shrinkage produce the most significant time-dependent effect on prestress losses, and research has shown that high performance and high strength concretes (HPC and HSC) exhibit less creep and shrinkage than conventional concrete. For this reason, the majority of traditional creep and shrinkage models and methods for estimating prestress losses, over-predict the prestress losses of HPC and HSC girders. Nine HPC girders, with design compressive strengths ranging from 8,000 psi to 10,000 psi, and three 8,000 psi lightweight HPC (HPLWC) girders were instrumented to determine the changes in strain and prestress losses. Several creep and shrinkage models were used to model the instrumented girders. For the HPLWC, each model over-predicted the long-term strains, and the Shams and Kahn model was the best predictor of the measured strains. For the normal weight HPC, the models under-estimated the measured strains at early ages and over-estimated the measured strains at later ages, and the B3 model was the best-predictor of the measured strains. The PCI-BDM model was the most consistent model across all of the instrumented girders. Several methods for estimating prestress losses were also investigated. The methods correlated to high strength concrete, the PCI-BDM and NCHRP 496 methods, predicted the total losses more accurately than the methods provided in the AASHTO Specifications. The newer methods over-predicted the total losses of the HPLWC girders by no more than 8 ksi, and although they under-predicted the total losses of the normal weight HPC girders, they did so by less than 5 ksi.
Prestress Losses in Pretensioned High-strength Concrete Bridge Girders
Prestress Losses in Pretensioned High-strength Concrete Bridge Girders - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Prestress Losses in Pretensioned High-strength Concrete Bridge Girders write by Maher K. Tadros. This book was released on 2003. Prestress Losses in Pretensioned High-strength Concrete Bridge Girders available in PDF, EPUB and Kindle. "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.
Fibre Optic Methods for Structural Health Monitoring
Fibre Optic Methods for Structural Health Monitoring - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Fibre Optic Methods for Structural Health Monitoring write by Branko Glisic. This book was released on 2008-03-11. Fibre Optic Methods for Structural Health Monitoring available in PDF, EPUB and Kindle. The use of fibre optic sensors in structural health monitoring has rapidly accelerated in recent years. By embedding fibre optic sensors in structures (e.g. buildings, bridges and pipelines) it is possible to obtain real time data on structural changes such as stress or strain. Engineers use monitoring data to detect deviations from a structure’s original design performance in order to optimise the operation, repair and maintenance of a structure over time. Fibre Optic Methods for Structural Health Monitoring is organised as a step-by-step guide to implementing a monitoring system and includes examples of common structures and their most-frequently monitored parameters. This book: presents a universal method for static structural health monitoring, using a technique with proven effectiveness in hundreds of applications worldwide; discusses a variety of different structures including buildings, bridges, dams, tunnels and pipelines; features case studies which describe common problems and offer solutions to those problems; provides advice on establishing mechanical parameters to monitor (including deformations, rotations and displacements) and on placing sensors to achieve monitoring objectives; identifies methods for interpreting data according to construction material and shows how to apply numerical concepts and formulae to data in order to inform decision making. Fibre Optic Methods for Structural Health Monitoring is an invaluable reference for practising engineers in the fields of civil, structural and geotechnical engineering. It will also be of interest to academics and undergraduate/graduate students studying civil and structural engineering.
Investigation of Transfer Length, Development Length, Flexural Strength, and Prestress Losses in Lightweight Prestressed Concrete Girders
Investigation of Transfer Length, Development Length, Flexural Strength, and Prestress Losses in Lightweight Prestressed Concrete Girders - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Investigation of Transfer Length, Development Length, Flexural Strength, and Prestress Losses in Lightweight Prestressed Concrete Girders write by Thomas E. Cousins. This book was released on 2003. Investigation of Transfer Length, Development Length, Flexural Strength, and Prestress Losses in Lightweight Prestressed Concrete Girders available in PDF, EPUB and Kindle. Encouraged by the performance of high performance normal weight composite girders, the Virginia Department of Transportation has sought to exploit the use of high performance lightweight composite concrete (HPLWC) girders to achieve economies brought about by the reduction of dead loads in bridges. Transfer length measurements (conducted on two AASHTO Type IV HPLWC prestressed girders) indicated an average transfer length of 17 inches, well below the AASHTO and ACI requirements. Two HPLWC AASHTO Type II girders and a 48 x 8 inch normal weight 4000-psi concrete deck were fabricated. The girders were cast of concretes with a compressive strength of 6380 psi and a unit weight of 114 pcf. Full scale testing of the girders was conducted to evaluate development length and flexural strength in HPLWC composite girders. Embedment lengths of five, six, and eight feet were evaluated. Tests indicated a development length of about 72 inches, marginally below the ACI and AASHTO requirements. All tested girders exceeded their theoretical flexural capacity by 24% to 30%. A third composite Type II girder was cast of high performance normal weight concrete and topped with a 48 x 8 inch normal weight 4000-psi concrete deck. This girder was intended as a control specimen. Prestress losses in the HPLWC AASHTO Type IV girders monitored over a nine-month period were found to be less than those calculated using the ACI and PCI models.
Instrumentation and Monitoring of High Performance Concrete Prestressed Bridge Girders
Instrumentation and Monitoring of High Performance Concrete Prestressed Bridge Girders - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Instrumentation and Monitoring of High Performance Concrete Prestressed Bridge Girders write by Vellore S. Gopalaratnam. This book was released on 2001. Instrumentation and Monitoring of High Performance Concrete Prestressed Bridge Girders available in PDF, EPUB and Kindle.
