Structural Behavior of Strengthened Concrete-Encased Steel Beams with Web Openings

Concrete-encased steel beams (CESB) have become one of the fundamental composite members utilized in recent years. The research aims to investigate the effect of strengthening CESB with and without openings. Eleven simply supported fully CESB beams with and without web opening under static loading using a four-point loading system were studied. Two main stages were considered; studying the effect of the presence of web opening (located in the shear zone), and the effect of applying three different strengthening materials on the flexure or the shear zone of the beams on the behavior of the CESB. Carbon fiber-reinforced polymer wraps, glass fiber-reinforced polymer wraps, and steel plates were used as externally bonded reinforcement strengthening materials. The obtained experimental results were the mode of failure, the crack pattern, load–deflection curve at mid-span, load–strain curves at different locations, first crack load, serviceability load, ultimate load, energy absorption, and ductility ratio. A Finite-Element Analysis (FEA) is performed using ANSYS release 19.0 program to simulate the 11 tested specimens. Test outcomes showed that the ultimate load and its corresponding deflection decreased by about 58.28% and 80.17%, respectively, due to the effect of the web opening. Furthermore, shear strengthening of CESB with web opening located in the shear zone is more effective than the flexural strengthening using the three different strengthening materials. Also, using a steel plate is extra effective than using carbon fiber wraps or glass fiber wraps on the performance of the tested beams. Based on the FEA, high compatibility between both FE and experimental results is achieved.