1# Library to Find Best eBook for Read
Author : Fred Wayne Klaiber
Release : 1993
Genre : Bridges
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis Strengthening of an Existing Continuous-span, Steel-stringer, Concrete-deck Bridge by : Fred Wayne Klaiber
Download or read book Strengthening of an Existing Continuous-span, Steel-stringer, Concrete-deck Bridge written by Fred Wayne Klaiber. This book was released on 1993. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Release : 1990
Genre : Bridges
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis Strengthening of an Existing Continuous-span, Steel-beam, Concrete-deck Bridge by Post-tensioning by :
Download or read book Strengthening of an Existing Continuous-span, Steel-beam, Concrete-deck Bridge by Post-tensioning written by . This book was released on 1990. Available in PDF, EPUB and Kindle. Book excerpt: The need to upgrade a large number of understrength and obsolete bridges in the U.S. has been well documented in the literature. Through several Iowa DOT projects, the concept of strengthening simple-span bridges by post-tensioning has been developed. The purpose of the project described in this report was to investigate the use of post-tensioning for strengthening continuous composite bridges. In a previous, successfully completed investigation, the feasibility of strengthening continuous, composite bridges by post-tensioning was demonstrated on a laboratory 1/3-scale-model bridge (3 spans: 41 ft 11 in. x 8 ft 8 in.). This project can thus be considered the implementation phase. The bridge selected for strengthening was in Pocahontas County near Fonda, Iowa, on County Road N28. With finite element analysis, a post-tensioning system was developed that required post-tensioning of the positive moment regions of both the interior and exterior beams. During the summer of 1988, the strengthening system was installed along with instrumentation to determine the bridge's response and behavior. Before and after post-tensioning, the bridge was subjected to truck loading (1 or 2 trucks at various predetermined critical locations) to determine the effectiveness of the strengthening system. The bridge, with the strengthening system in place, was inspected approximately every three months to determine any changes in its appearance or behavior. In 1989, approximately one year after the initial strengthening, the bridge was retested to identify any changes in its behavior. Post-tensioning forces were removed to reveal any losses over the one-year period. Post-tensioning was reapplied to the bridge, and the bridge was tested using the same loading program used in 1988. Except for at a few locations, stresses were reduced in the bridge the desired amount. At a few locations flexural stresses in the steel beams are still above 18 ksi, the allowable inventory stress for A7 steel. Although maximum stresses are above the inventory stress by about 2 ksi, they are about 5 ksi below the allowable operating stress; therefore, the bridge no longer needs to be load-posted.
Author : Terry J. Wipf
Release : 2003
Genre : Concrete bridges
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis Evaluation of Post-tension Strengthened Steel Girder Bridge Using FRP Bars by : Terry J. Wipf
Download or read book Evaluation of Post-tension Strengthened Steel Girder Bridge Using FRP Bars written by Terry J. Wipf. This book was released on 2003. Available in PDF, EPUB and Kindle. Book excerpt: Many state, county, and local agencies are faced with deteriorating bridge infrastructure composed of a large percentage of relatively short to medium span bridges. In many cases, these older structures are rolled or welded longitudinal steel stringers acting compositely with a reinforced concrete deck. Most of these bridges, although still in service, need some level of strengthening due to increases in legal live loads or loss of capacity due to deterioration. Although these bridges are overstressed in most instances, they do not warrant replacement; thus, structurally efficient but cost-effective means of strengthening needs to be employed. In the past, the use of bolted steel cover plates or angles was a common retrofit option for strengthening such bridges. However, the time and labor involved to attach such a strengthening system can sometimes be prohibitive. This project was funded through the Federal Highway Administration's Innovative Bridge Research and Construction program. The goal is to retrofit an existing structurally deficient, three-span continuous steel stringer bridge using an innovative technique that involves the application of post-tensioning forces; the post-tensioning forces were applied using fiber reinforced polymer post-tensioning bars. When compared to other strengthening methods, the use of carbon fiber reinforced polymer composite materials is very appealing in that they are highly resistant to corrosion, have a low weight, and have a high tensile strength. Before the post-tensioning system was installed, a diagnostic load test was conducted on the subject bridge to establish a baseline behavior of the unstrengthened bridge. During the process of installing the post-tensioning hardware and stressing the system, both the bridge and the post-tensioning system were monitored. The installation of the hardware was followed by a follow-up diagnostic load test to assess the effectiveness of the post-tensioning strengthening system. Additional load tests were performed over a period of two years to identify any changes in the strengthening system with time. Laboratory testing of several typical carbon fiber reinforced polymer bar specimens was also conducted to more thoroughly understand their behavior. This report documents the design, installation, and field testing of the strengthening system and bridge.
Author :
Release : 1993
Genre : Bridge approaches
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis Practical Solutions for Bridge Strengthening & Rehabilitation by :
Download or read book Practical Solutions for Bridge Strengthening & Rehabilitation written by . This book was released on 1993. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Release : 1989
Genre : Bridges
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis Alternate Methods of Bridge Strengthening by :
Download or read book Alternate Methods of Bridge Strengthening written by . This book was released on 1989. Available in PDF, EPUB and Kindle. Book excerpt: The need for upgrading a large number of understrength and obsolete bridges in the United States has been well documented in the literature. Through the performance of several Iowa DOT projects, the concept of strengthening bridges (simple and continuous spans) by post-tensioning has been developed. The purpose of this project was to investigate two additional strengthening alternatives that may be more efficient than post-tensioning in certain situations. The research program for each strengthening scheme included a literature review, laboratory testing of the strengthening scheme, and a finite-element analysis of the scheme. For clarity the two strengthening schemes are presented separately. In Part 1 of this report, the strengthening of existing steel stringers in composite steel beam concrete-deck bridges by providing partial end restraint was shown to be feasible. Part 2 of this report summarizes the research that was undertaken to strengthen the negative moment regions of continuous, composite bridges. Two schemes were investigated: post-compression of stringers and superimposed trusses within the stringers.
