为保证桁架结构的安全性，在结构设计中进行可靠性计算是必要环节。桁架结构由于杆件截面各异，空间组成复杂，杆件连接焊缝多样，使原本困难的桁架结构可靠性计算变得更加复杂而繁琐。现有计算方法大多分别考虑杆件和连接焊缝的失效模式，再考虑各失效模式下桁架结构载荷的重分布影响，而忽略了杆件和焊缝各种失效模式之间的干涉关系。文中将杆件及其端部的连接焊缝作为一个单元，通过建立单元失效干涉数学模型，推导出受压弯载荷杆件和焊缝的失效干涉判定公式，计算各种失效模式的概率失效带，绘制单元失效干涉图，确定模糊可靠性的应用范围，得出杆件在缓慢加载失效模式不产生干涉的载荷变化幅度。%In order to ensure the safety of structure,reliability calculation is necessary for the truss structure design. Since of truss number cross-section is different,spatial composition is complex,attachment weld is Diversity,so that the original is difficult to calculate the reliability of the truss structure becomes more complex and cumbersome.For effect on truss overall load redistribution,in the existing calculation method,all the failure modes of steel nmber and attachment weld are calculated.But the interference of stel nmber and attachment weld failure modes are igngred.Steel number and attachment weld are considered as a unit and the interference of unit failure modes figure are drew,through calculating the range of different failure modes and building interference model of unit failure modes.The judgment formula of interference of unit failure modes is deduced.The aplication conditions of the fuzzy reliability is obtained,the load range of slowly load-ing unit which does not produce interference of failure modes is obtained.
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