Experimental study of shear transfer in slim floor systems using precast concrete hollow core slabs and steel beam with web circular opening

Steel-concrete slim flooring system using precast concrete hollow core slabs and steel beam with web openings is an innovative construction system designed to combine the high bending resistance of both precast prestressed hollow core slabs and steel beam with web openings. This system can provide floor systems with a minimum constructional depth in comparison with ordinary composite floors. The aim of this study was to evaluate in an exploratory way the shear transferring mechanism between the steel beam with circular web opening and the precast hollow-concrete slab. The shear connection is formed by in-situ concrete passes through the web openings and infill the voids of the precast slabs. One push-out test was conducted to investigate the shear transferring mechanism of shear connection and the experimental results were compared to analytical methods. The shear resistance of the shear connection was predicted with good accurate by analytical methods.

A review on the behaviour of reinforced concrete beams with fibre-reinforced polymer-strengthened web openings

Web openings often need to be created in reinforced concrete (RC) beams for the passages of utility ducts and/or pipes. Such web openings reduce the cross-section area of the beam in the affected region, leading to decrease in its load-carrying capacity and stiffness. Therefore, a fibre-reinforced polymer (FRP)-strengthening system generally needs to be applied around the web opening to ensure the safety of the weakened beam. A number of studies have been conducted by researchers all over the world to examine the behaviour of RC beams with FRP-strengthened web opening/web openings, and plenty of useful findings have been generated. This article presents a critical literature review of existing relevant research from three aspects: experimental studies, numerical studies and theoretical studies. The effect of main factors, including the size, shape, location and number of the web opening, the shape and shear span ratio of the beam, the concrete strength, the loading scheme and the FRP-strengthening scheme, on the structural performance of RC beams with FRP-strengthened web opening/web openings have been thoroughly analysed and discussed. Finally, directions for future research based on the gaps which exist in existing studies are pointed out.

ENHANCING OF FLEXURAL STRENGTH OF WEB OPENING REINFORCED GEOPOLYMER BEAMS BY USING FRP STRIPS

This study is devoted to inspect the flexural behavior of Geopolymer reinforced concrete beams with “large” web transverse opening and strengthened by three kinds of Fiber Reinforced Polymer materials. The implemented experimental program comprised casting eight beams under static and “one stage” repeated load, two of these are normal concrete beams and the others are Geopolymer beams. These beams are divided into two groups, the first comprised four beams of solid and beams “with transvers web opening” under static load for normal and Geopolymer concrete beams. The second group are of four Geopolymer beams that one of them is “un strengthened and having transvers web opening” while the others are also have transvers web opening but strengthened by different kinds of Fiber Reinforced Polymer materials sheets that installed vertically aligned and accompanied with the 90mm diameter large circular web opening. The strengthening materials included are Carbon Fiber Reinforced Polymer, Glass fiber Reinforced Polymer and Hybrid (one layer of Glass + one layer of Carbon) reinforced polymer sheets. The results showed that for the ultimate load capacity was decreased by 9.96% for holed normal concrete beam if compared with solid normal concrete solid beam while such capacity was decreased 2.25% and 11.89% for solid and holed Geopolymer beams respectively. In addition to that, the maximum load capacity is also decreased by 8.16%, 10.20% and 12.25% for Glass, Carbon and Hybrid fiber reinforced polymer strengthened beams if compared with reference beams “holed un strengthened beam” subjected to cyclic load.

Reinforcement Schemes for Cold-Formed Steel Joists with a Large Web Opening in Flexural Zone - An Experimental Investigation

The objective of this investigation is to develop an economical and an efficient reinforcement scheme for large web openings in cold-formed steel (CFS) joists in flexural zones that would restore the original moment resistance of the section. This investigation considered commonly used floor joists in North American CFS construction. Tests on joists webs with no openings and with large circular and square openings located at the mid-depth revealed that large openings may reduce the flexural strength by 23%. A reinforcement scheme consisting of screw fastening of 31.75 mm x 12.7 mm (1-1/2”x1/2”) bridging channels having matching thickness as of the receiving joist, along the compression and the tensile edges of the opening utilizing a screw spacing of 31.75 mm was established. Three identical tests utilizing the proposed reinforcement scheme restored the corresponding flexural strengths of the CFS section under consideration, and the failure locations were outside the reinforced opening regions.

Experimental-Analytical Study of CFRP strengthening Effect of Reinforced Concrete Beams with Web Opening under Torsion and Bending

— The strength of reinforced concrete beams is reduced to high extent when openings are created in their webs, so it is necessary to strengthen these beams by any modern strengthening methods to restore the strength of the beams before openings are created in their webs to continue in use of these beams. Analytical study is presented in this research to study CFRP strengthening effect around created opening in reinforced concrete beams under torsion and bending. The research depends on finite element method using Ansys 15. It is used SOLID65 to model concrete beam, SOLID 185 to model CFRP, supports and steel arms, and LINK 181 for long steel and stripes. Then analytical model is built to model reinforced concrete beams. This model gives results which are closed to experimental results.