动力荷载作用下拱形立体桁架损伤及失效机理

Damage and failure mechanism of steel arch truss under dynamic loads

研究拱形立体桁架在动力荷载作用下2种可能的失效机理：由于几何非线性起主要作用引起的动力失稳和由于塑性变形过度发展导致的强度破坏。考虑损伤累积效应以及几何初始缺陷等因素的影响,对某拱形立体桁架在简谐荷载以及地震荷载作用下,杆件屈服比率、结构最大节点位移、结构总应变能和结构塑性位移等响应进行分析,得到动力荷载作用下结构的倒塌破坏模式,求出相应的极限荷载。对拱形立体桁架在地震下的动力性能进行参数化分析。研究结果表明：考虑损伤累积效应时,拱形立体桁架破坏加速度降低2 2.3%~4 6.7%;考虑L/3 0 0初始几何缺陷时,破坏加速度降低2.8%~1 1.1%。

Two kinds of failure mechanism, i.e. dynamic instability mainly due to the second-order effect and the strength failure mainly due to the excessive development of plastic deformations under dynamic loads of steel arch truss were studied. Cases of steel arch truss subjected to harmonic actions and earthquake waves were analyzed considering damage cumulative effect and initial geometrical imperfection. The dynamic responses of plastic element ratio, displacement of the key joint, strain energy and plastic displacement of steel arch truss were investigated. The failure mode of structure under various dynamic loads and the corresponding ultimate load were obtained. When the ground motion record was input, the dynamic properties of steel arch truss were analyzed. The results show that when damage cumulative effect is considered, the failure acceleration of steel arch truss structure decreases 22.3%-46.7%; when L/300 initial geometric imperfection is considered, the failure acceleration decreases 2.8%-11.1%.