Steel and steel-concrete composite girders are two types of girders commonly used for long-span bridges. However, practice has shown that the two types of girders have some drawbacks. For steel girders, the orthotropi...Steel and steel-concrete composite girders are two types of girders commonly used for long-span bridges. However, practice has shown that the two types of girders have some drawbacks. For steel girders, the orthotropic steel deck (OSD) is vulnerable to fatigue cracking and the asphalt overlay is susceptible to damage such as rutting and pot holes. While for steel-concrete composite girders, the concrete deck is generally thick and heavy, and the deck is prone to cracking because of its low tensile strength and high creep. Thus, to improve the serviceability and durability of girders for long-span bridges, three new types of steel-UHPC lightweight composite bridge girders are proposed, where UHPC denotes ultra-high performance concrete. The first two types consist of an OSD and a thin UHPC layer while the third type consists of a steel beam and a UHPC waffle deck. Due to excellent mechanical behaviors and impressive durability of UHPC, the steel-UHPC composite girders have the advantages of light weight, high strength, low creep coefficient, low risk of cracking, and excellent durability, making them competitive alternatives for long-span bridges. To date, the proposed steel-UHPC composite girders have been applied to 14 real bridges in China. It is expected that the application of the new steel-UHPC composite girders on long-span bridges will have a promising future.展开更多
In this study,a fully precast steel—ultrahigh performance concrete(UHPC)lightweight composite bridge(LWCB)was proposed based on Mapu Bridge,aiming at accelerating construction in bridge engineering.Cast-in-place join...In this study,a fully precast steel—ultrahigh performance concrete(UHPC)lightweight composite bridge(LWCB)was proposed based on Mapu Bridge,aiming at accelerating construction in bridge engineering.Cast-in-place joints are generally the controlling factor of segmental structures.Therefore,an innovative girder-to-girder joint that is suitable for LWCB was developed.A specimen consisting of two prefabricated steel—UHPC composite girder parts and one post-cast joint part was fabricated to determine if the joint can effectively transfer load between girders.The flexural behavior of the specimen under a negative bending moment was explored.Finite element analyses of Mapu Bridge showed that the nominal stress of critical sections could meet the required stress,indicating that the design is reasonable.The fatigue performance of the UHPC deck was assessed based on past research,and results revealed that the fatigue performance could meet the design requirements.Based on the test results,a crack width prediction method for the joint interface,a simplified calculation method for the design moment,and a deflection calculation method for the steel—UHPC composite girder in consideration of the UHPC tensile stiffness effect were presented.Good agreements were achieved between the predicted values and test results.展开更多
某斜拉桥的次边跨和中跨的桥面板采用8 mm平钢板+15 cm UHPC层+PBL剪力键的新型组合体系。桥面板预制段UHPC依靠阶梯式燕尾榫湿接缝连接。为研究该组合桥面板湿接缝的负弯矩静力性能,制作足尺模型试件进行试验。通过施加荷载,测量各级...某斜拉桥的次边跨和中跨的桥面板采用8 mm平钢板+15 cm UHPC层+PBL剪力键的新型组合体系。桥面板预制段UHPC依靠阶梯式燕尾榫湿接缝连接。为研究该组合桥面板湿接缝的负弯矩静力性能,制作足尺模型试件进行试验。通过施加荷载,测量各级荷载下桥面板试件的位移、应变,并观测裂缝,获得荷载-位移曲线、荷载-应变曲线、裂纹发展规律和破坏形态。研究结果表明:阶梯式燕尾榫湿接头接缝处的抗裂能力、承载能力与湿接头非接缝处性能大体相当,开裂后其刚度逐渐退化;裂纹宽度0.2 mm时,荷载关系从线性变为非线性;到达极限荷载后,桥面板仍保持良好的延性;PBL剪力键能确保钢与UHPC形成整体,保证两者共同变形;桥面板裂纹主要集中在现浇段,多而密;跨中截面处钢筋和混凝土的应变均大于其他部位的,试件破坏以跨中裂纹宽度急剧增加为标志。展开更多
基金The authors would like to thank the following funders for providing support to this research: the National Key Research and Development Program of China (No. 2018YFC0705400)the National Natural Science Foundation of China (Grant Nos. 51778223 and 51708200)the Major Program of Science and Technology of Hunan Province (No. 2017SK1010).
文摘Steel and steel-concrete composite girders are two types of girders commonly used for long-span bridges. However, practice has shown that the two types of girders have some drawbacks. For steel girders, the orthotropic steel deck (OSD) is vulnerable to fatigue cracking and the asphalt overlay is susceptible to damage such as rutting and pot holes. While for steel-concrete composite girders, the concrete deck is generally thick and heavy, and the deck is prone to cracking because of its low tensile strength and high creep. Thus, to improve the serviceability and durability of girders for long-span bridges, three new types of steel-UHPC lightweight composite bridge girders are proposed, where UHPC denotes ultra-high performance concrete. The first two types consist of an OSD and a thin UHPC layer while the third type consists of a steel beam and a UHPC waffle deck. Due to excellent mechanical behaviors and impressive durability of UHPC, the steel-UHPC composite girders have the advantages of light weight, high strength, low creep coefficient, low risk of cracking, and excellent durability, making them competitive alternatives for long-span bridges. To date, the proposed steel-UHPC composite girders have been applied to 14 real bridges in China. It is expected that the application of the new steel-UHPC composite girders on long-span bridges will have a promising future.
基金The authors gratefully acknowledge the following support:National Key R&D Program(No.2018YFC0705400)National Natural Science Foundation of China(Grant No.51778223)+1 种基金Major Program of Science and Technology of Hunan Province(No.2017SK1010)The authors also express their sincere appreciation to the reviewers of this paper for their constructive comments and suggestions.
文摘In this study,a fully precast steel—ultrahigh performance concrete(UHPC)lightweight composite bridge(LWCB)was proposed based on Mapu Bridge,aiming at accelerating construction in bridge engineering.Cast-in-place joints are generally the controlling factor of segmental structures.Therefore,an innovative girder-to-girder joint that is suitable for LWCB was developed.A specimen consisting of two prefabricated steel—UHPC composite girder parts and one post-cast joint part was fabricated to determine if the joint can effectively transfer load between girders.The flexural behavior of the specimen under a negative bending moment was explored.Finite element analyses of Mapu Bridge showed that the nominal stress of critical sections could meet the required stress,indicating that the design is reasonable.The fatigue performance of the UHPC deck was assessed based on past research,and results revealed that the fatigue performance could meet the design requirements.Based on the test results,a crack width prediction method for the joint interface,a simplified calculation method for the design moment,and a deflection calculation method for the steel—UHPC composite girder in consideration of the UHPC tensile stiffness effect were presented.Good agreements were achieved between the predicted values and test results.
文摘某斜拉桥的次边跨和中跨的桥面板采用8 mm平钢板+15 cm UHPC层+PBL剪力键的新型组合体系。桥面板预制段UHPC依靠阶梯式燕尾榫湿接缝连接。为研究该组合桥面板湿接缝的负弯矩静力性能,制作足尺模型试件进行试验。通过施加荷载,测量各级荷载下桥面板试件的位移、应变,并观测裂缝,获得荷载-位移曲线、荷载-应变曲线、裂纹发展规律和破坏形态。研究结果表明:阶梯式燕尾榫湿接头接缝处的抗裂能力、承载能力与湿接头非接缝处性能大体相当,开裂后其刚度逐渐退化;裂纹宽度0.2 mm时,荷载关系从线性变为非线性;到达极限荷载后,桥面板仍保持良好的延性;PBL剪力键能确保钢与UHPC形成整体,保证两者共同变形;桥面板裂纹主要集中在现浇段,多而密;跨中截面处钢筋和混凝土的应变均大于其他部位的,试件破坏以跨中裂纹宽度急剧增加为标志。
