FRP strengthening of shear walls with openings

Abstract

Concrete shear walls are one of the main lateral resisting members in buildings. The functional requirements like architectural and even mechanical requirements entail that openings have to be installed in structural walls as well as floors. In this study, nonlinear static analysis was utilized to study the effects of fiber reinforced plastic (FRP) on the ultimate load capacity of concrete shear walls with openings using the finite element analysis software ABAQUS. In order to verify the accuracy of the numerical model, a comparison was done between the results of experimental and numerical analysis of a concrete shear wall. Subsequent to verification of the Finite Element Model (FEM), the effects of creating cutoff openings as well as strengthening effects of applying FRP have been studied. Whereas the numerical results show good correlation between the FEM and the experimental results of reinforced concrete (RC) shear walls, the numerical analysis represents a remarkable improvement in ultimate lateral load capacity of shear wall with opening strengthened using fiber reinforced plastic. The results obtained are presented in relative diagrams and tables.

Performance of Strengthened, Reinforced Concrete Shear Walls with Opening

“…When conducting experimental tests, the technique would not continue until the wall was entirely destroyed and collapsed. The test would often continue until a peak strength decrease of between 75-80% was noticed, or it would be stopped if the test specimen exhibited the concrete spalling mode of failure [38,39]. In our research, the failure loads occurred either by the failure of GFRP sheets or by concrete crushing.…”

“…Both results were then compared to determine the load capacity loss after installing the opening, and these results served as a baseline for choosing working load values of other un-strengthened walls with various openings. Furthermore, the findings of Behfarnia et al [39] were helpful for estimating the working load values; for walls with an opening area of 6.25%, the working load was about (50-75%) of the ultimate load of control shear wall; for walls with an opening area of 11.11%, the working load was approximately (40-50%) of ultimate load of control shear wall; and for walls with an opening area of 25%, the working load was about (30-40%) of ultimate load of control shear wall, and considering the above-mentioned data and the appearance of developed diagonal cracks on each wall specimen, the working load value was carefully selected.…”

“…All RC shear walls were cast with the same dimensions of 750 mm width, 750 mm height (h w /l w = 1), and 70 mm thickness, monolithically connected to an upper and lower beam. These dimensions were tested by Lefas et al [38]; the arrangement of opening and the scheme of the applied GFRPs were proposed by Behfarnia et al [39]. The upper beam dimensions (1150 mm × 200 mm × 150 mm) functioned as the element through which axial and horizontal loads were applied to the walls and as a cage for the anchorage of the vertical bars.…”

Structural behavior of FRP-strengthened reinforced concrete shear walls with openings using finite element method

“…It was found that the bearing capacity of the shear walls with openings was improved with CFRP reinforcement and consequently with reduction of active stresses in the upper corner of the opening. Behfarnia and Sayah (2012) conducted theoretical studies on the impact of openings in shear walls reinforced with FRP sheets. Their results showed that the CFRP sheets caused maximum reinforcement in shear walls with opening with an area of 25% (relative to the total area of the wall) associated with 39% increase in capacity.…”