Effect of Web Openings on Flexural Behaviour of Underground Metro Station RC Beams under Static and Cyclic Loading

Abstract

This paper investigates the influence of multiple transverse web openings on the flexural behaviour of underground metro station reinforced concrete (RC) beams. This problem is outlined with an actual underground engineering project, in which the web opening used in the RC beams violates the current specifications. A total of five beams with different numbers of web openings are fabricated and tested under static and cyclic loading conditions, thereby simulating actual operations in unfavourable conditions. The results suggest that the existence of the openings decreases the loadbearing capacity, ductility, stiffness, and energy dissipation ability of the RC beams. Moreover, the results show that the corners of the openings are the weakest parts of the beams. However, additional reinforcements around the openings can partially mitigate the impact of the openings on the loadbearing and seismic performance of the RC beams. The laboratory experiments presented herein not only provide guidelines for the use of RC beams with web openings in actual engineering projects, especially underground projects where RC beams with web openings have seldom been investigated, but also shed light on improving the related design specifications.

Review of the Structural Performance of Beams and Beam–Column Joints with Openings

“…Experimental studies on RC beam-column joints with openings on the beam web have demonstrated the effectiveness of various reinforcement strategies in improving their cyclic performance. For example, researchers have found that the provision of supplementary transverse reinforcement around the openings can enhance the confinement of the concrete, thereby increasing the joint's load-carrying capacity and energy dissipation under cyclic loading [38]. Moreover, extending longitudinal reinforcement through the openings and providing adequate anchorage can ensure better force transfer and maintain the structural integrity of the joint.…”

Behavior of Reinforced Concrete Beams with Vertically Penetrated Holes across the Cross ‐ Sectional Depth

“…It has been shown that the influence of the openings on the load-bearing and seismic performance of the RC beams can be reduced by adding extra reinforcements around the openings. Openings' configuration was investigated in and an increase in ultimate load capacity when circular openings were used was reported [11]. These codes typically cover aspects such as load combinations, material properties, structural analysis, reinforcement detailing, and construction practices relevant to RC beams.…”