钢筋混凝土桥墩弯剪扭抗震加固设计探讨

Study on Flexure-shear-torsion Seismic Strengthening Design of Reinforced Concrete Piers

针对曲线桥梁钢筋混凝土(Reinforced Concrete,RC)桥墩,在已有抗震加固措施的基础上,提出一种考虑弯、剪、扭耦合作用的桥墩新型抗震加固措施:采用分段凹凸钢纤维混凝土预制壳壁沿桥墩全高进行加固,并在壳壁内部设置无粘结钢筋。阐述了该加固措施的加固机理,并提出了弯、剪、扭抗震加固设计方法,同时基于平截面假定理论推导了加固后桥墩的抗弯承载力和抗扭承载力计算公式。通过实际算例表明,在扭矩由凹凸钢纤维混凝土预制壳壁承担并保证抗扭承载力不致降低的前提下,加固后桥墩的屈服弯矩、极限弯矩较加固前提高近一倍,达到了设计目标,且本文建议的公式计算值与XTRACT计算值十分接近,验证了公式的正确性和有效性。

On the basis of existing seismic strengthening methods,a new seismic strengthening measure considering the interaction of shear force,flexural moment and torsional moment for curved bridge reinforced concrete(RC)pier was proposed in this paper.The concave convex precast segments made of steel fiber concrete were adopted to reinforce the RC pier along the height,and the unbonded reinforcements were arranged inside the segments.The strengthening mechanism of the measure was expounded,and design technique of flexure shear torsion seismic strengthening was presented.Meanwhile,based on the assumption of plane cross section,the formulas of flexural capacity and torsion capacity of strengthening pier were deduced.A calculation example shows that under the condition that torque is borne by the segments and the torsion capacity of strengthening pier is not decreased,both yield moment and ultimate bending moment almost have been doubled than RC pier,and that means the design goal has been achieved.The value calculated by formula of flexural capacity keeps in good agreement with its value calculated by XTRACT,the correctness and validity of the formula are verified.