空腹式变截面连续梁桥V形结构受力性能分析

Mechanical Behavior Analysis of V-shaped Structure of Open-web Continuous Beam Bridge with Variable Section

以国内首座含V形结构的钢混混合连续梁桥为工程背景,明确其施工阶段和成桥运营阶段下的受力状态,掌握其受力特性和关键部位的应力分布情况;开展参数分析,提出该类桥梁的设计优化建议。结果表明:可采用临时扣索支架联合施工空腹式钢混混合连续梁桥主V形结构,施工过程中结构受力均满足规范要求;施工阶段V形结构下弦整体受压,上弦整体受拉,最不利施工阶段为浇筑上弦混凝土阶段,最大拉应力2.2 MPa,处于下弦中部顶板处;成桥运营阶段V形结构下弦整体受拉,上弦整体受压,上弦顶板最大拉应力2.5 MPa,最大压应力18 MPa;随着V形结构夹角的增大,上下弦交汇处截面承受的弯矩逐渐减小,顶板应力也逐渐减小;保持关键截面应力大小不变的情况下,V形结构主梁梁高随夹角的增大而减小,V形结构夹角在125°~145°区间时总造价较经济。

Based on the first steel-concrete hybrid continuous beam bridge with V-shaped structure in China,the stress state in the construction stage and the operation stage of the bridge is analyzed.The stress characteristics and the stress distribution information of key parts is also discussed.The parameter analysis is carried out,and the design optimization suggestions of this kind of bridge is proposed.The results are as follows.The main V-shaped structure of open web steel-concrete hybrid continuous beam bridge can be constructed with temporary cable support,and the structural stress in the construction stage can meet the specification requirements;during the construction stage,the lower chord of the V-shaped structure is under overall compression,while the upper chord is under overall tension,and the most unfavorable construction stage is the pouring of the upper chord concrete stage,with the maximum tensile stress of 2.2 MPa,which is located in the middle roof of the lower chord.During the operation stage of the bridge,the lower chord of the V-shaped structure is under tension condition,while the upper chord is under compression condition.The maximum tensile stress of the upper chord roof is 2.5 MPa,and the maximum compressive stress is 18 MPa.With the increase of the angle of the V-shaped structure,the bending moment at the intersection of the upper chord and the lower chord is gradually reduced,and the roof stress is also gradually reduced.Under the condition of keeping the stress of the key section unchanged,the beam height of the main beam of the V-shaped structure decreases with the increase of the angle,and the V-shaped structure is stable.The total cost is more economical when the angle of the V-shaped structure is between 125°and 145°.