混凝土剪力墙受剪承载力可靠度分析

针对我国规范未对剪力墙受剪承载力可靠指标进行校准,本文研究钢筋混凝土剪力墙受剪承载力的可靠度水平.根据剪力墙抗剪公式所依据的试验及试件情况,收集并筛选截面型式、混凝土类型、配筋型式、破坏形态等方面与其一致的74片剪力墙试验数据,对试件承载力的试验值与规范公式计算值进行分析,得出剪力墙受剪承载力计算模式不定性统计参数,进而得出抗力统计参数和概率分布类型;采用考虑基本变量概率分布类型的验算点法进行可靠指标计算.结果表明:现行规范剪力墙受剪承载力可靠指标低于目标可靠指标3.7的要求,其中荷载效应比、剪跨比、轴向压力、配筋率、混凝土强度等级对可靠指标影响较小,风荷载与永久荷载效应比对可靠指标影响较大,分布钢筋采用HPB300时的可靠指标在同等条件下较小.为保证剪力墙受剪承载力可靠指标满足目标可靠指标要求,引入承载力调整系数0.95对现行计算公式进行修正,修正后计算公式的可靠指标均值为3.738.

Reliability Analysis of Shear Capacity of Concrete Shear Walls

Current Chinese design codes have not calibrated the reliable index of shear capacity of shear wall. In order to study the reliability level of shear bearing capacity of reinforced concrete shear wall, this paper collected and selected 74 shear wall specimens that are consistent with the ones based on the shear formulas of shear wall in terms of section type, concrete type, reinforcement type and failure mode. By analyzing the test and calculated values of shear capacity for the specimens, the statistical parameters of calculation model uncertainty were obtained, and then the statistical parameters and probability distribution types of resistance were obtained. The checking point method considering the probability distribution of basic variables was used to calculate the reliability index. The results show that the reliability index of shear capacity of shear wall in current code is lower than the target reliability index 3.7. Load effect ratio, shear span ratio, axial pressure, reinforcement ratio and concrete strength grade have little influence on the reliability index. The wind-to-dead load ratio has great influence on the reliability index. The reliability index of distributed rebar with HPB300 is small under the same conditions. In order to ensure that the reliability index of shear capacity of shear wall meets the requirements of target reliability index, a bearing capacity adjustment coefficient of 0.95 is introduced to modify the current calculation formula. The average value of reliable index in the revised formula is 3.738.