【摘要】 通过非线性静力Pushdown分析及灵敏度计算方法,对影响多层装配式混凝土框架结构抗连续倒塌性能的不确定性参数进行评估。首先以某牛腿-插销杆-角钢连接形式的全装配式混凝土框架子结构静载试验研究为基础,利用OpenSees有限元软件对该试验过程进行数值模拟,计算所得的结构荷载-位移曲线及失效模式均与试验结果较好吻合。在此基础上,对试验过程中的插销杆失效模式进行了参数优化分析,结果表明可通过增大螺杆直径或采用高强螺杆等方式增强插销杆的抗剪强度,从而有效提高结构二次防倒塌能力;其次,设计了一榀四跨七层的全装配式混凝土框架结构及相应的现浇结构,分别对拆除首层中柱和边柱两种不同失效工况下剩余结构的抗连续倒塌性能进行了非线性静力Pushdown计算;并通过选取包含荷载、材料以及结构几何尺寸等在内的15个不确定性参数,利用Tornado图形法对各不确定性参数的灵敏度进行了分析。结果表明,在中柱和边柱失效工况下,该多层全装配式框架结构在压拱阶段的极限承载能力分别较现浇结构低约18.5%和22.8%左右;同时纵筋屈服强度、混凝土抗压强度、楼面恒荷载、活荷载及梁纵筋截面积等不确定性参数对采用该连接形式的整体结构抗连续倒塌性能影响较大,而混凝土弹性模量、柱纵筋截面积、纵筋弹性模量、箍筋截面积以及梁宽尺寸等参数不确定性对结构性能影响相对较小,在结构设计阶段可忽略其变异性造成的影响。更多还原

【Abstract】 In this paper, the nonlinear static Pushdown method and the sensitivity analysis method were utilized in the process of progressive collapse evaluation of the multi-story precast concrete(PC) structures influenced by the uncertain parameters. Firstly, the numerical analysis was conducted in OpenSees program based on the static test results of a fully assembled PC structure with the dowel rob joint connections. The analysis results revealed that both of the calculated load-displacement relationship and failure patterns were well agreed with the test results. Meanwhile, the parametric study was conducted according to the test failure mode of dowel rob, and it was revealed that the secondary progressive collapse performance of PC structure was effectively improved via employing the dowel rob with larger diameter or shear strength. Secondly, a 4-span 7-story fully assembled PC structure and reinforced concrete(RC) were built in OpenSees based on the calibrated model, and the Pushdown analysis was conducted for the residual structure with middle/exterior column loss scenario, respectively. Meanwhile, totally 15 uncertain parameters(i.e., load conditions, material properties, specimen dimensions, etc.) were selected to conduct the sensitivity analysis based on the Tornado method. the calculation results has revealed that the ultimate loading capacity of PC structure at compressive arch action was approximately 18.5% and 22.8% times lower than the corresponding RC structure under the two scenarios, respectively. Meanwhile, the uncertain parameters of rebar yielding strength, concrete compressive strength, dead loads, live loads and cross-section of beam rebar has placed an important in the progressive collapse resistance mechanism of PC structures. However, the discreteness influence of concrete elasticity modulus, cross-section of column rebar, rebar elasticity modulus, cross-section of stirrup and beam width was relative lower of the structural performance, which can be ignored during the structure design progress.更多还原