乍甸1号大桥钢-混凝土组合梁桥面优化设计  

Optimal Design of Slabs of Steel-Concrete Composite Beam of Zhadian No.1 Bridge

作　　者：陈全胜 侯圣均 蒋晨晨 汤唯宇 刘入瑞 CHEN Quan-sheng;HOU Sheng-jun;JIANG Chen-chen;TANG Wei-yu;LIU Ru-rui(Powerchina Roadbridge Group Co. ,Ltd. ,Beijing 100089,China;Key Laboratory of Civil Engineering Safety and Durability of Ministry of Education,Tsinghua University,Beijing 100084,China)

机构地区：[1]中电建路桥集团有限公司,北京100089 [2]清华大学土木工程安全与耐久教育部重点实验室,北京100084

出　　处：《世界桥梁》2022年第4期25-31,共7页World Bridges

基　　金：国家自然科学基金项目(51978376)。

摘　　要：乍甸1号大桥主桥为钢-混凝土组合连续梁桥,原方案采用全预制桥面板,支座处采用加厚托座,并在负弯矩区段布置预应力筋。由于桥址位于山区,墩高较大,原方案施工不便,且负弯矩区段桥面板易开裂,需对桥面结构和施工方案进行优化设计。优化桥面结构采用“预制板+后浇层”叠合板桥面,取消托座,单块板吊装重量由33.81 t减少至2.06 t,在负弯矩区段桥面布置50 mm厚高延性工程水泥基复合材料(ECC)层;取消预应力筋,采用支座顶升方式向负弯矩区段桥面板导入预压力。采用MIDAS Civil软件建立模型,模拟优化后桥面整体顶升和分次顶升2种方案的施工过程,对钢梁应力、桥面板应力、施工阶段整体变形、桥面板裂缝宽度进行计算。结果表明:2种方案各指标均符合规范要求,整体顶升方案优于分次顶升方案,最终采用整体顶升方案;根据最大裂缝宽度计算结果,确定ECC布置在支座两侧各10 m的桥面范围,具有较好的经济性。The main bridge of Zhadian No.1 Bridge is a steel-concrete continuous beam bridge.In the original design,the slabs combined with the steel beams were all precast concrete slabs,thickened brackets were added at the locations of bearings and prestressing tendons were tensioned in the negative bending moment zones.However,multiple challenges made the design hard to be realized,including the mountainous environment,high-rise piers,and cracking-vulnerable negative bending moment zones.Both the deck structure and construction scheme were modified.After optimization,the original precast concrete slab deck was changed to the composite deck of precast slabs and post-pouring course,the brackets at the bearings were canceled,and the lifting weight of a single concrete panel was reduced from 33.81 t to 2.06 t.A 50 mm-thick high-ductility engineered cementitious composite(ECC)course was applied in the negative bending moment zone,and the prestressing tendons in the original design were removed.Already-installed steel girders at supports were jacked up first,once the casting of the concrete slabs was completed,the steel girders were lowered to introduce pre-compression to the concrete slabs.A finite element model was developed by MIDAS Civil to simulate the construction processes of the two solutions after optimization,namely integral jack-up and phased jack-up.The stresses in the steel beam,integral deformation during construction,crack widths of deck slabs were computed.According to the analysis,the indexes of both the solutions could meet the code requirements.The integral jack-up solution is superior to the phased jack-up,which is finally selected.According to the calculated maximum crack width,placing the ECC course within the 10 m range at both sides of the bearing can achieve better economic effect.

关 键 词：钢-混凝土组合梁桥 叠合板 抗裂措施 支座顶升 工程水泥基复合材料 结构设计 

分 类 号：U448.216[建筑科学—桥梁与隧道工程] U442.5[交通运输工程—道路与铁道工程]