吊杆断裂破坏安全极限状态下中、下承式拱桥悬吊桥面系简化计算方法

Simplified calculation method for suspension bridge deck system of half⁃through and through arch bridge under safety limit condition of suspender fracture

为简化吊杆断裂后中、下承式拱桥剩余结构动力响应的计算方法,提出悬吊桥面系强健性设计破坏安全极限状态,开展了大比例缩尺模型试验,采用ANSYS/LS-DYNA建立不考虑拱肋的悬吊桥面系结构有限元模型,提出弹性支撑悬吊桥面系简化计算模型,并采用五弯矩普通方程式,对弹性支撑悬吊桥面系计算长度进行简化,推导得到了悬吊桥面系简化计算方法;构建18种不同跨径标准拱桥的分析结果验证简化计算方法精度。研究结果表明:破坏安全极限状态恒载γG和活载γQ分项系数分别为1.2和0.9,1车道、2车道、3车道及以上的荷载横向分布系数分别取1.0、0.75和0.52,钢筋和钢结构强度分别取1.25倍和1.05屈服强度、其他材料强度取标准值;不考虑拱肋的悬吊桥面系结构有限元简化计算模型最大正误差仅为11.7%;建议短吊杆、次短吊杆以及长吊杆断裂工况下弹性支撑连续梁模型计算长度分别取D+2L、D+3L和4L,其偏差率分别为2.89%、2.40%、3.66%。吊杆断裂破坏安全极限状态下中、下承式拱桥悬吊桥面系简化计算方法的最大正误差分别为11.4%和10.1%,计算结果具有良好的精度且偏于安全。

To simplify the calculation method of the dynamic response of the half⁃through and through arch bridges after the suspender fracture,the breaking safety limit state for the robust design of suspension bridge deck was proposed.The scale model test was carried out,and the finite element(FE)model of the suspension bridge deck structure without considering the arch ribs was established by ANSYS/LS⁃DYNA.A simplified calculation model of elastic support continuous beam was proposed,and a simplified calculation method of suspension bridge deck system was derived by using the ordinary equation of five bending moments.18 standard arch bridges with different spans were analyzed to verify the accuracy of the simplified calculation method.The results show that the partial coefficients of constant load and live load in the breaking safety limit state areγG=1.2 andγQ=0.9,respectively,and the lateral load distribution coefficients are 1.0 for 1 lane,0.75 for 2 lanes,and 0.52 for lanes and above,and the rebar and steel strengths are taken as 1.25 and 1.05 times of yield strengths,respectively,the other materials strength are taken as standard values.The maximum positive error of the FE simplified calculation model is 11.7%.It is suggested that the calculated lengths of the elastic support continuous beam model under the fracture con⁃dition of short suspender,sub⁃short suspender and long suspender be D+2L,D+3L and 4L respectively,and the deviation rates be 2.89%,2.40%and 3.66%,respectively.The maximum positive errors of the simplified calculation method under the safety limit of suspender fracture are 11.4%and 10.1%,respectively,and the calculation results have good accuracy with bias towards safety.