Biaxial Bending Analysis of the Slabs under Concentrated Loads

Crack is one of the most common defects observed in reinforced concrete slabs. Based on experimental results, it is observed that the biaxial bending effect of slabs with center concentrated load is very obvious, especially on the slabs with larger width to length ratio or smaller loading areas. According to the conventional design method, the longitudinal reinforcement is calculated according to the transverse moment, while the transverse reinforcement is determined according to the minimum ratio of reinforcement. It is found that longitudinal cracks in concrete structures may occur due to insufficient transverse reinforcement. This paper presents a technique for analyzing the transverse reinforcement of slabs with center concentrated loads. Twelve slabs are tested for this purpose. By studying transverse and longitudinal moments, coefficients to describe the uneven level of their distributions are induced. One simplified methods are proposed to calculate the ratio of transverse reinforcement effetely.