Shear Test of Variable Depth RC Beams with Inflection Point

¹ Southeast University, Key laboratory of concrete and pre-stressed concrete structures of Ministry of Education, 210096 Nanjing, China
² Nanjing Forestry University, College of Civil Engineering, 210037 Nanjing, China

^* Corresponding author: k.zheng@njfu.edu.cn

Abstract

Variable depth continuous box girder bridges are widely used recently. However, the influence mechanism of the inflection point and variable depth on the shear behaviour of this type bridge has not been fully understood. In this paper, reinforced concrete (RC) beams with constant depth and variable depth were designed as constrained beams to create the inflection point. Firstly, a theoretical uncoupling theory for shear and flexural deformation of variable depth beam was derived. Then, the after cracking shear deformations and the ultimate failure loads were measured. Further, preliminary reveal of the influence mechanism of inflection point on the shear capacity was attempted. Finally, the development of after-cracking shear strain and the degradation of shear stiffness were studied. The formation of first critical diagonal cracks and yielding of stirrup are the turning points of shear stiffness. Increasing stirrup ratio provides more apparent enhancement for residual shear stiffness, which means more effective inhibition on shear deformation.