CFRP strengthening of steel plate girders with web openings subjected to shear and bending (original) (raw)
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The effectiveness of CFRP strengthening of steel plate girders with web opening subjected to shear
MATEC Web of Conferences, 2018
The present study is experimental by nature; it involves applying shear buckling test on seven steel-plated girders that are subjected to shear loading. Four of these girders represent the strengthened girders whereas the other three are reference girders. One of the latter type of girders has a square web opening; the second has a diamond web opening while the last one has no opening at all. The webs of the strengthened girders were adhesively attached to CFRP sheets of different patterns. This step was carried out to evaluate the most effective strengthening scheme by CFRP composite. The study aims at examining the effect of several parameters on the behavior of web girders. It further examines the percentage of increase in the ultimate shear capacity of the perforated girders that have a fixed location and size where the latter is equal to 40 percent of the web depth. Results have shown that, first, the ultimate shear load of the CFRP-strengthened girders with square web opening ...
Shear Strengthening of Composite Steel-Concrete Girders with Web Openings Using CFRP Sheets
International Journal of Engineering & Technology, 2018
This study presents an experimental investigation of subjecting one-point load at mid-span of five composite steel-concrete girders that are loaded predominantly in shear. Three of girders are reference girders with no web openings, square web openings, and circular web openings, respectively. The both other girders are strengthened girders. The compressive strength of concrete, slab reinforcement and all dimensions of girders are kept. The CFRP laminates were adhesively attached to the webs of strengthened girders in various patterns and were done to estimate the effect of strengthening scheme by CFRP composite on increasing of the ultimate load capacity of the web openings girders. The research purposes to examine the behavior and effect of increasing in the ultimate shear capacity of strengthened girders that have constant dimensions and locations of web openings which is about 40 % of web depth. The results show the increase in ultimate load capacity of strengthened girders cont...
Effect of CFRP Layer Orientation on the Behavior of Shear-Strengthened Steel Plate Girders
Engineering and Technology Journal, 2018
The present paper investigates experimentally the impacts of fiber layer orientation on the structural behavior of CFRP strengthened steelplated girders that are subjected to shear. Three of these girders were considered strengthened girders whereas the last one represents the reference girder. Each of the four steel-plated girders was tested aside and in different periods of time using the shear buckling test. A point load was applied to the center of the top flange of the four girders using Avery hydraulic machine. A laminated carbon fiber reinforced polymer sheet (CFRP) was fully adhesively attached to the web area of the three girders. The attached carbon fiber sheet took different patterns: either on one side or on both sides. Such a step helps to evaluate the most effective strengthening technique of each of the girders using CFRP composite. To check the behavior and the increase in the ultimate shear capacity of the girders, several parameters were examined. Results have revealed that both the unstrengthen and strengthened girders of different orientations of CFRP showed a similar stiffness behavior at a relatively low load levels. However, when the load is increased, the stiffness behavior significantly is increased in the three strengthened girders, compared to the strengthened girders. It has further shown that the ultimate shear load of the three strengthened girders were higher than that of the reference girder. Such a result can clearly be exemplified by the obtained ranges: 19.5 6% and 25% depending on the orientation of the CFRP laminates. Following Von Mises stresses, the researcher was able to predict the ultimate shear load of the four girders and to figure out the arrived at results from the four experimental tests.
CFRP STRENGTHENING OF STEEL BEAMS WITH WEB OPENINGS
Integration of services via web-openings in steel floor beams is often unavoidable in modern frame buildings. Such web-openings can significantly reduce the shear and bending strength capacity of the beams. Traditionally, the welding of additional steel plates to the opening areas is adopted as a means of strengthening and stiffening. This not only presents practical difficulties but can induce residual stresses which weaken fatigue performance of the section. This study explores the use of externally bonded carbon fibre reinforced polymer composites (CFRP) as an alternative means of strengthening. Using a non-linear finite element approach, the effect of strengthening arrangement is investigated with a view to finding the most structurally efficient layout. For the series studied significant enhancements of strength comparable to those achieved by welded plates, have been predicted.
The result of an experimental programme investigating a novel technique to strengthen web plates of steel plate girders against breathing fatigue is presented in this paper. The programme was divided into five phases, including: (1) the development of a novel preformed corrugated FRP panel for strengthening thin-walled steel plate girder webs against buckling, (2) selecting the appropriate adhesive and epoxy using double-lap shear and tension specimens, (3) producing the FRP panel, and (4, 5) testing its performance in two main experimental series. The initial series involved tests on 13 steel plates strengthened with the proposed preformed corrugated FRP panel and subjected to in-plane shear loading using a specially manufactured “picture frame” arrangement designed to induce the appropriate boundary conditions and stresses in the web plates of realistic plate girders; a description of this novel testing approach is included. This initial test series investigated the performance of different forms of strengthening under static load, in preparation for a subsequent series of cyclic tests to investigate their fatigue performance. The test variables included FRP type (CFRP or GFRP), form of FRP (closed or open section), number of FRP layers, and orientation of GFRP fibres used to build the FRP panel. This paper focuses on the second series, in which six specimens were manufactured to simulate the end panel of a 15m plate girder. These were strengthened with the optimized FRP panel from the first series and tested for shear buckling under repeated cyclic loading. Test results and non-linear finite element modelling showed the efficiency of the technique at reducing the critical stresses and increasing the fatigue life of the girders. Finally, the most appropriate strengthening method for fatigue performance is given on the basis of the work presented herein.
Composite Structures
The result of an experimental programme investigating a novel technique to strengthen web plates against breathing fatigue is presented in this paper; the programme was divided into five phases, including: (1) the development of a novel preformed corrugated FRP panel for strengthening thin-walled steel plate girder webs against buckling, (2) selecting the adequate adhesive and epoxy using double-lap shear and tension specimens, (3) producing the FRP panel, and (4, 5) testing its performance in two main experimental series; the initial (static) series and the final (cyclic) series. Only the initial series which involved tests on 13 steel plates strengthened with the proposed preformed corrugated FRP panel and subjected to inplane shear will be reported in this paper. This series investigated the performance of different forms of strengthening under static load, in preparation for a subsequent series of cyclic tests to investigate their fatigue performance. Test results showed the efficiency of the technique at increasing the stiffness of the strengthened specimens in comparison to the unstrengthened ones and reducing the critical stresses which will serve as a precursor for the anticipated increase in the fatigue life of the girders.
Experimental investigation of CFRP-strengthened steel beams with web openings
Journal of Constructional Steel Research
The introduction of web openings in existing steel floor beams is a common occurrence in practice. Such modifications are often necessary to accommodate additional services driven by a change of building use, thus extending the service life of the structure. Depending on their size and location, openings in the web can present a major challenge to the strength and stiffness of the beam. Strengthening around an opening is often necessary to maintain the required performance of the floor beam, traditionally this is affected via application of additional steel plate, either bolted or welded. This paper focusses on the novel application of carbon fibre reinforced polymer (CFRP) to the problem of strengthening web openings, taking advantage of the material's ease of handling, superior strength-to-weight ratio and corrosion resistance. An experimental study involving 4 full scale universal beams was conducted in order to investigate the ability of CFRP to recover the strength and stiffness of beams following the introduction of web openings. All the specimens were tested under 6-point bending in the experiments. For further comparison, the equivalent test series without the addition of strengthening was modelled numerically via finite element analysis.. The effectiveness of the strengthening technique was demonstrated with increases in the load carrying capacity over the unaltered beam of between 5 and 20% being achieved.
CFRP shear strengthening system for steel bridge girders
Engineering Structures, 2018
This paper presents an investigation undertaken to study the effectiveness of using small-diameter CFRP strands for shear strengthening of steel bridge girders. The study includes a comprehensive experimental program to study effects of the CFRP reinforcement ratio and orientation of the strands. An analytical model, calibrated by the experimental tests, was used to provide design recommendation. Results of the study showed that the proposed strengthening system is effective in increasing the shear capacity of steel bridge girders and there was no sign of CFRP debonding or rupture failure commonly observed by CFRP laminates up to approximately 80% of the steel yield stress.
Shear Strengthening of Composite Concrete Steel Plate Girders with Web Openings Using Steel Strips
IOP Conference Series: Materials Science and Engineering, 2020
The study aims to investigate behaviour plus influence on the final load resistance of strengthen girders containing openings in web which were 40% of web height. This paper presents an experimental study of applying of five steel-concrete composite plate girder specimens that were loaded in shear predominantly. Three of those girders were considered as control girders, without web openings, containing circular web holes, and containing square web holes, respectively. Other two girders were strengthen girders. The slab reinforcement, dimensions of girders and compressive strength of concrete slabs were constant. Strengthening was made by using steel rings and strips which were welded to webs of strengthen girders to investigate influence of strengthening plan by steel welding on behaviour and final load strength for these girders. Findings illustrate increasing in final load strength of strengthen girders with circular and square web holes with about 57.38% and 43.75%, respectively in comparing to that for control girders. Moreover, the final shear capacity for the tested girders was also compared with that predicted by von Mises stresses.
Behavior of Steel Plate Girders with Web Openings Loaded in Shear
2013
The structural behavior of three steel plate girders under shear is studied. The first one is the reference plate girder (G) which is prepared without web openings, and the second one (GO) is fabricated to contain circular opening at the center of each web panel, the diameter of the opening is 60% of the web depth, while the third plate girder (GOR) is with reinforced strip welded around the circular web openings. The aspect ratio of the panels is one and they all have the same dimensions. The experimental results obtained from second and third plate girders have been compared with those obtained from the reference plate girder. The comparison indicates that the reduction in the ultimate shear load for plate girder with web opening is 51% and for the plate girder with reinforced web opening is 35%. Also through the experimental results, new formulas are presented to predict the ultimate shear load of perforated steel girders with large openings. A nonlinear finite element analysis i...