Experimental study of beams with stiffened large web openings

The use of beams with isolated openings in the webs is common in steel structures. However, the presence of large openings in the web generates specific mechanical behavior in comparison with that of solid web beams and leads quite often to the reinforcement of the opening by welding stiffeners. An experimental program based on thirteen steel beams with a single rectangular web opening is performed. It aims to evaluate the influence of the openings reinforced or not by stiffeners on the behavior of the beam loaded in shear and bending. The stiffeners are used to increase the resistance of the openings. Different solutions are compared using various positions and lengths of stiffeners in the longitudinal and vertical directions. The comparisons are based on the failure load, the stiffness and the strain distribution. The experimental results and observations show the efficiency and the limits of the different studied solutions of stiffening. It has been observed that long horizontal stiffeners were the best stiffening solution. Furthermore, the use of double or single sided stiffeners showed that in both cases, they improve significantly the ultimate carrying capacity of the beam as long as the anchorage length is sufficient. The results can be used as a basis to develop numerical and analytical models.