钢筋混凝土梁抗剪承载力的FASTM显式计算方法

FASTM Explicit Calculation Method for Shear Bearing Capacity of Reinforced Concrete Beams

针对传统FASTM抗剪承载力模型需多次迭代计算的特点,在对245片有腹筋RC矩形截面简支梁抗剪极限状态下混凝土、钢筋受力行为进行统计分析后,对钢筋、混凝土本构关系进行适当简化并引入具有显著统计意义的回归关系,提出了有腹筋RC矩形截面简支梁抗剪承载力的显式计算方法。研究结果表明:抗剪承载力极限状态下245片试验梁箍筋均发生屈服,混凝土主拉应变均超过开裂应变,混凝土主压应变均大于峰值应力对应的应变,虽然有少许试验梁的纵筋应变大于其屈服应变,但在统计意义上纵筋应变显著小于其屈服应变,且混凝土剪应变与箍筋拉应变、箍筋拉应变与混凝土拉应变之间均有极为显著的相关关系,将其作为附加控制方程并对钢筋、混凝土本构关系适当简化即可实现抗剪承载力的显式求解;FASTM的抗剪承载力理论预测结果确实会受剪跨比影响,当剪跨比在1.5~3.0之间时FASTM显式算法能较为准确地计算梁体的抗剪承载力。

In view of the characteristics of the traditional fastm shear bearing capacity model which needs many iterations,after statistical analysis of the behavior of concrete and reinforcement under the shear limit state of 245 simply supported RC rectangular section beams with web reinforcement,the constitutive relationship of reinforcement and concrete was appropriately simplified,and the regression relationship with significant statistical significance was introduced,and the shear bearing capacity of RC rectangular section simple supported beam with web reinforcement was proposed.An explicit calculation method was proposed.The results show that in the ultimate state of shear capacity,the stirrups of 245 test beams yield,the main tensile strain of concrete exceeds the cracking strain,and the principal compressive strain of concrete is greater than the strain corresponding to the peak stress.Although the strain of longitudinal reinforcement of a few test beams is greater than its yield strain,the strain of longitudinal reinforcement is significantly less than its yield strain in statistical sense,and the shear strain and hoop of concrete are significantly lower than the yield strain.At the same time,there is a significant correlation between the tensile strain of reinforcement and stirrup and the tensile strain of concrete.As an additional governing equation,the explicit solution of shear capacity can be achieved by properly simplifying the constitutive relationship of reinforcement and concrete.The theoretical predicted of FASTM’s shear capacity is indeed affected by the shear span ratio.When the shear-span ratio is between 1.5 and 3.0,FASTM explicit algorithm can accurately calculate the shear capacity of beams.