Experimental and numerical study on strengthening of UHPFRC deep beams with square openings using CFRP and WWM configurations
Aref A. Abadel, Yousef R. Alharbi
Abstract
In modern construction, it is often necessary to route utility pipes through reinforced concrete (RC) beams. These pipes facilitate the transmission of electrical, communications, water, sanitary, and other services. This phenomenon is particularly prevalent in RC deep beams, particularly when the stories' heights are relatively low. RC deep beams that have shear issues are more susceptible to failure, requiring retrofitting and the resolution of shear issues, even though they may have similar transverse reinforcements to traditional RC beams. The current study conducted experimental and numerical analyses to examine the strengthening of deep beams constructed using an ultra-high-performance fiber-reinforced concrete (UHPFRC) mixture with a square web opening. Two strengthening techniques were used: welded wire mesh (WWM) and carbon-fiber-reinforced polymer (CFRP) strip. Five deep beams subject to testing using a four-point flexural loading method. The deep beams measure 150 × 300 x 1000 mm in width, depth, and length, respectively. Within the crucial shear zone, the square opening (measuring 100 mm) was implemented at the intersection of the compression strut lines. The findings revealed that the presence of a square opening reduced the load-carrying capacity of the deep beam by 56.5 % compared to the solid deep beam. The ultimate load of the strengthened specimens with WWM and CFRP strips increased by a ratio that reached up to 63.8 % compared to unstrengthened specimens with the opening. The strengthening of the deep beams succeeded in reducing the effect of the opening, reducing the loss in shear strength from 56.5 % to 37.4 %, compared with the control deep beam. 3D simulated finite element (FE) models using ABAQUS software confirmed the experimental findings by accurately predicting failure patterns and load-midspan deflection curves.