交叉撑杆和抗滑移下弦索段的张弦梁结构抗连续倒塌动力试验研究OA

To overcome the inherent limitations of conventional beam string structures,such as low structural redundancy and vulnerability to progressive collapse,a beam string structure incorporating cross-struts and anti-slip connections between lower cable segments was proposed.Following the alternative load path(ALP)methodology,an initial cable rupture trigger device and a physical test model for anti-progressive collapse assessment were designed and constructed.High-frequency measurement systems for dynamic strain,displacement,and cable force were employed to perform dynamic progressive collapse tests.The investigation focused on structural response characteristics,collapse progression mechanisms,and internal force redistribution following mid-span cable section failures.It is found that the electromagnetic-lever activation device effectively simulates cable rupture.After cable failure,the lower diagonal struts in the damaged zone experience instantaneous stress increase,becoming key structural components to resist progressive collapse.Under the design case,the composite truss action formed by the upper chord beam and cross-struts successfully redistributes the unbalanced forces through reconstructed load paths,achieving a maximum displacement of 63 mm,which is approximately 1/100 of the span length and effectively preventing structural collapse.In ultimate capacity case,initial lower cable rupture triggers sequential tensile failures of adjacent struts,leading to the loss of truss action and plastic hinge formation at the upper chord beam's mid-span,which then extend to the connections with upper diagonal struts,causing local buckling and subsequent structural collapses.