超静定组合结构桥梁受力特性的3D-FEM模拟分析
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摘要
钢—混凝土复合结构桥梁作为不同于钢桥和混凝土桥的第三类桥梁正受到世界桥梁界的重视。它可以较好的发挥钢材和混凝土材料各自的优点，弥补各自的弱点，使得桥梁建设更加经济合理，所以，在公路、铁路新建桥梁领域(如梁桥、刚构、拱桥、斜拉桥等)以及既有桥梁维修加固方面，得到越来越广泛的应用。对组合结构桥梁的设计理论、结构形式和构造细节、施工方法等方面的研究已经取得了很大进展，但仍然存在许多问题需要深入研究和完善，例如：混凝土板裂纹控制、接合刚度对结构受力性能的影响、设计与施工的依存性等。为此，本文在总结各国研究成果的基础上，利用大型通用结构分析程序MSC／NASTRAN和MSC／PATRAN，对超静定组合梁桥的受力特性进行了分析研究，目的是推动这一结构形式在中国的应用和发展。其中重点研究了组合结构桥梁中剪力键性能，负弯矩区混凝土板裂纹状态及控制裂纹的设计方法，钢与混凝土的接合刚度和施工方法对结构受力特性的影响，以及混合结构桥梁中梁墩刚性连接的传力途径及应力分布等。主要研究成果如下：
(1)连续组合结构桥梁和复合结构桥梁刚节点的3D-FEM计算模型的建立
应用MSC／NASTRAN和MSC／PATRAN建立了较精确的连续组合梁桥和连续复合刚构桥刚节点的三维有限元计算模型。提出了以正交的两个平行于钢和混凝土界面的弹簧单元及一个垂直于界面的多点约束(MPC)单元来模拟剪力键，以小间隙接触(Gap)单元来模拟混凝土桥面板的开裂，模型中忽略了混凝土板与钢梁接触面间由摩阻而产生的粘着力。该计算模型较好地实现了组合梁和混合梁受力性能(应力和位移)的模拟分析，并具较高的计算精度。
(2)栓钉型剪力键承载力的3D-FEM分析
针对当前剪力键一般通过费时费力的推顶试验来确定抗剪刚度和极限承载力的状况，本文利用MSC／NASTRAN非线性模块实现了对栓钉剪力键推顶试样的数值模拟分析，数值计算结果与试验结果能够很好吻合。这使得通过有限元方法的模拟和少量实物试验的验证，就能确定栓钉剪力键的剪切刚度和极限承载力，可以大大节省时间和经费。
(3)连续组合梁负弯矩区控制裂纹的设计方法
分析了连续组合梁负弯矩区混凝土板裂纹的产生机制，裂纹与内力(弯矩M、轴力N)和内力重分配的相互关系，裂纹对组合梁抗弯刚度的影响，并介绍了裂纹宽度计算
铁道科学研究院博士学位论文
方法和限制裂纹宽度的设计方法等，以利于在工程实际中正确认识组合梁桥负弯矩区混
凝土板开裂对结构受力的影响，以及采用更合理的限制裂纹设计法，提高组合梁的耐久
性。
O）接合刚度对连续组合梁桥受力特性的影响
以三跨连续组合梁桥为算例，详细分析了连续组合梁桥中钢和混凝土接合刚度的变
化（剪力键不同抗剪刚度和匹配布置的变化）以及双层组合对结构受力特性的影响。分
析认为，应以剪力键承载力和抗剪刚度相结合的设计概念代替过去只考虑剪力键承载力
的设计概念；连续组合梁的正弯矩区和负弯矩区配置相同或不同抗剪刚度的剪力键均是
可行的：负弯矩区设置柔性剪力键时可以有效限制裂纹产生，但需用加强钢筋来分散剪
力键承担的剪力集中；沿全桥长范围配置刚性剪力键，可以有效降低钢梁分担的弯矩，
减缓剪力键承担的剪力集中，但需采用钢纤维混凝土等措施来限制负弯矩区裂纹宽度；
双层组合不仅可以提高中间支点处的截面刚度，减小挠度，而且截面更经济。该研究结
果可为组合结构桥梁设计规范的修改和完善提供理论依据。
（5）组合梁桥施工方法与设计的相互关系
针对连续组合梁桥的承载结构体系和加载顺序随施工方法不同而不断变化的特点，
通过对临时支架法、中间支点升降法、调整混凝土板施工顺序法三种常用施工方法下的
三跨连续组合梁桥内力和变形的计算，首次系统地分析了上述三种施工方法对结构内
力、变形和各支点反力的调整能力。分析认为，采用中间支点升降法与调整混凝土板施
工顺序相结合的施工方法，不仅可以避免负弯矩区混凝土裂纹，还可以合理调整钢梁和
混凝土板的内力，并使端支点与中间支点反力更均匀，使组合梁桥的结构更加经济合理。
分析结果有利于连续组合梁桥选择合理的施工方法及设计和施工方法的有机统一，进而
有利于促进我国组合梁桥设计和施工技术的发展。
（6）连续复合刚构桥（混合结构）墩梁刚性连接传力的3D－FEM分析
应用有限元方法证实了连续复合刚构桥墩梁刚性节点采用剪力键连接方式可以有
效的传递内力，而且使节点的施工性得到极大改善。分析结果有利于复合刚构桥的设计
和应用。
The steel-concrete hybrid bridge, which is the third kind of bridge different from the steel bridge and the concrete bridge, is being attached importance by the world bridge engineering circles. In this kind of bridge, the advantages of steel and concrete material can be exerted respectively and thoroughly to fetch up each other's failings to make the bridge construction more economical and reasonable. So it has been being used more and more widely in railway and highway engineering in the new bridge construction, including the girder bridge, the rigid frame bridge, the arch bridge, the cable-stayed bridge and so on, and in the reinforcement construction of the existed bridge. Though great progress has been achieved on researches on the design theory, structural type, structure details and construction method of the composite bridge, there are still many problems, such as crack control of the concrete deck, influence of the connecting rigidity over the structural mechanical characteristics and mutual depende
ncy between design and construction, need deeper researches for better solutions. Hence, on the basis of research achievements of other countries, the mechanical characteristics of the statically indeterminate composite bridge is analyzed in this thesis by utilizing the large universal finite element software, MSC/NASTRAN and MSC/PATRAN, to promote the application and development of the composite bridge in China. The emphases of the research works of this thesis are laid on the mechanical performance of the shear connector of the continuous composite bridge, the crack status and design method for crack control of the concrete deck in the negative moment zone of the continuous composite bridge, the influence of the connecting rigidity and the construction method over the structural mechanical characteristics of the continuous composite bridge, and the force transmission mechanism and the stress distribution of the rigid node connecting the girder and the pier in the mixed bridge and so on. The main research a
chievements are as the followings:
(1) Establishment of the 3D-FEM models of the continuous composite bridge and the rigid node of the continuous hybrid bridge
Relatively exact 3D-FEM models of the continuous composite bridge and the rigid node of the continuous hybrid rigid frame bridge are established through MSC/NASTRAN and MSC/PATRAN. The author advances that the shear connector is simulated by two spring elements, which are vertical to each other and parallel to the interface between steel and concrete, and one multipoint constraint element, MPC element, which is vertical to the interface. The author also puts forward that the crack of the deck is simulated by the Gap element which can't support longitudinal tensile force but can support longitudinal compressive force. In the model, the bonding force between steel and concrete cause by friction and block is neglected. These models can be used to analyze the mechanical performance, stress and displacement, oi the composite bridge and hybrid bridge very well and have relatively high precision.
(2) 3D-FEM analysis for the load-bearing capacity of the stud connector
As the prevailing method to determine the shear rigidity and the limit load-bearing capacity of the shear connector is the push test, which is time consuming and laborious, in this thesis the push tesi specimen of the stud connector is simulated through the non-linear analysis module of the MSC/NASTRAN and the numerical analysis results are in good coherence with that of the practicality lev; As a result, the shear rigidity and the limit load-bearing capacity of the stud connector can be determined by the finite element method and only a few practicality verification tests. Consequently time and cost can be saved greatly.
(3) Design method for controlling cracks in the negative moment zone of the continuous composite girder
The crack mechanism of the concrete deck in the negative moment zone of the coniinuous composite girder, the relationship between the crack and the int
(1)连续组合结构桥梁和复合结构桥梁刚节点的3D-FEM计算模型的建立
应用MSC／NASTRAN和MSC／PATRAN建立了较精确的连续组合梁桥和连续复合刚构桥刚节点的三维有限元计算模型。提出了以正交的两个平行于钢和混凝土界面的弹簧单元及一个垂直于界面的多点约束(MPC)单元来模拟剪力键，以小间隙接触(Gap)单元来模拟混凝土桥面板的开裂，模型中忽略了混凝土板与钢梁接触面间由摩阻而产生的粘着力。该计算模型较好地实现了组合梁和混合梁受力性能(应力和位移)的模拟分析，并具较高的计算精度。
(2)栓钉型剪力键承载力的3D-FEM分析
针对当前剪力键一般通过费时费力的推顶试验来确定抗剪刚度和极限承载力的状况，本文利用MSC／NASTRAN非线性模块实现了对栓钉剪力键推顶试样的数值模拟分析，数值计算结果与试验结果能够很好吻合。这使得通过有限元方法的模拟和少量实物试验的验证，就能确定栓钉剪力键的剪切刚度和极限承载力，可以大大节省时间和经费。
(3)连续组合梁负弯矩区控制裂纹的设计方法
分析了连续组合梁负弯矩区混凝土板裂纹的产生机制，裂纹与内力(弯矩M、轴力N)和内力重分配的相互关系，裂纹对组合梁抗弯刚度的影响，并介绍了裂纹宽度计算
铁道科学研究院博士学位论文
方法和限制裂纹宽度的设计方法等，以利于在工程实际中正确认识组合梁桥负弯矩区混
凝土板开裂对结构受力的影响，以及采用更合理的限制裂纹设计法，提高组合梁的耐久
性。
O）接合刚度对连续组合梁桥受力特性的影响
以三跨连续组合梁桥为算例，详细分析了连续组合梁桥中钢和混凝土接合刚度的变
化（剪力键不同抗剪刚度和匹配布置的变化）以及双层组合对结构受力特性的影响。分
析认为，应以剪力键承载力和抗剪刚度相结合的设计概念代替过去只考虑剪力键承载力
的设计概念；连续组合梁的正弯矩区和负弯矩区配置相同或不同抗剪刚度的剪力键均是
可行的：负弯矩区设置柔性剪力键时可以有效限制裂纹产生，但需用加强钢筋来分散剪
力键承担的剪力集中；沿全桥长范围配置刚性剪力键，可以有效降低钢梁分担的弯矩，
减缓剪力键承担的剪力集中，但需采用钢纤维混凝土等措施来限制负弯矩区裂纹宽度；
双层组合不仅可以提高中间支点处的截面刚度，减小挠度，而且截面更经济。该研究结
果可为组合结构桥梁设计规范的修改和完善提供理论依据。
（5）组合梁桥施工方法与设计的相互关系
针对连续组合梁桥的承载结构体系和加载顺序随施工方法不同而不断变化的特点，
通过对临时支架法、中间支点升降法、调整混凝土板施工顺序法三种常用施工方法下的
三跨连续组合梁桥内力和变形的计算，首次系统地分析了上述三种施工方法对结构内
力、变形和各支点反力的调整能力。分析认为，采用中间支点升降法与调整混凝土板施
工顺序相结合的施工方法，不仅可以避免负弯矩区混凝土裂纹，还可以合理调整钢梁和
混凝土板的内力，并使端支点与中间支点反力更均匀，使组合梁桥的结构更加经济合理。
分析结果有利于连续组合梁桥选择合理的施工方法及设计和施工方法的有机统一，进而
有利于促进我国组合梁桥设计和施工技术的发展。
（6）连续复合刚构桥（混合结构）墩梁刚性连接传力的3D－FEM分析
应用有限元方法证实了连续复合刚构桥墩梁刚性节点采用剪力键连接方式可以有
效的传递内力，而且使节点的施工性得到极大改善。分析结果有利于复合刚构桥的设计
和应用。
The steel-concrete hybrid bridge, which is the third kind of bridge different from the steel bridge and the concrete bridge, is being attached importance by the world bridge engineering circles. In this kind of bridge, the advantages of steel and concrete material can be exerted respectively and thoroughly to fetch up each other's failings to make the bridge construction more economical and reasonable. So it has been being used more and more widely in railway and highway engineering in the new bridge construction, including the girder bridge, the rigid frame bridge, the arch bridge, the cable-stayed bridge and so on, and in the reinforcement construction of the existed bridge. Though great progress has been achieved on researches on the design theory, structural type, structure details and construction method of the composite bridge, there are still many problems, such as crack control of the concrete deck, influence of the connecting rigidity over the structural mechanical characteristics and mutual depende
ncy between design and construction, need deeper researches for better solutions. Hence, on the basis of research achievements of other countries, the mechanical characteristics of the statically indeterminate composite bridge is analyzed in this thesis by utilizing the large universal finite element software, MSC/NASTRAN and MSC/PATRAN, to promote the application and development of the composite bridge in China. The emphases of the research works of this thesis are laid on the mechanical performance of the shear connector of the continuous composite bridge, the crack status and design method for crack control of the concrete deck in the negative moment zone of the continuous composite bridge, the influence of the connecting rigidity and the construction method over the structural mechanical characteristics of the continuous composite bridge, and the force transmission mechanism and the stress distribution of the rigid node connecting the girder and the pier in the mixed bridge and so on. The main research a
chievements are as the followings:
(1) Establishment of the 3D-FEM models of the continuous composite bridge and the rigid node of the continuous hybrid bridge
Relatively exact 3D-FEM models of the continuous composite bridge and the rigid node of the continuous hybrid rigid frame bridge are established through MSC/NASTRAN and MSC/PATRAN. The author advances that the shear connector is simulated by two spring elements, which are vertical to each other and parallel to the interface between steel and concrete, and one multipoint constraint element, MPC element, which is vertical to the interface. The author also puts forward that the crack of the deck is simulated by the Gap element which can't support longitudinal tensile force but can support longitudinal compressive force. In the model, the bonding force between steel and concrete cause by friction and block is neglected. These models can be used to analyze the mechanical performance, stress and displacement, oi the composite bridge and hybrid bridge very well and have relatively high precision.
(2) 3D-FEM analysis for the load-bearing capacity of the stud connector
As the prevailing method to determine the shear rigidity and the limit load-bearing capacity of the shear connector is the push test, which is time consuming and laborious, in this thesis the push tesi specimen of the stud connector is simulated through the non-linear analysis module of the MSC/NASTRAN and the numerical analysis results are in good coherence with that of the practicality lev; As a result, the shear rigidity and the limit load-bearing capacity of the stud connector can be determined by the finite element method and only a few practicality verification tests. Consequently time and cost can be saved greatly.
(3) Design method for controlling cracks in the negative moment zone of the continuous composite girder
The crack mechanism of the concrete deck in the negative moment zone of the coniinuous composite girder, the relationship between the crack and the int
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