Abstract
Guangdong Qingqiyong bridge is a prefabricated steel truss-concrete composite continuous rigid frame bridge with a span arrangement of 41 m + 70 m + 41 m, to prevent cracks of concrete deck on the bridge pier top section, prestress tendons are usually arranged inside of the concrete deck, after the connection between deck panels and steel truss, prestress tendons are tensioned to make deck compressed, it has been proved that this conventional prestress method is tedious for construction and it also results in a significant loss of prestress. In addition, stress of the top chords in the pier top section is very small in all construction stages, mainly ranges from -60 MPa to 50 MPa, thus failed to make full use of its material properties; therefore, preflex prestressing technology of steel truss concrete composite bridge (PPSC in short) was put forward based on preflex prestressing technology, then the detailed analysis was conducted. To validate the feasibility of PPSC, another case study-Wanzhou Bridge was carried out. Results show that the PPSC technology is feasible and it can avoid the use of prestress tendon, simplify the construction, make deck panels get the expected compressive stress easily and make full use of steel properties.
Highlights
Guangdong Qingqiyong Bridge, crossing Qingqiyong River, is a prefabricated steel truss-concrete composite continuous rigid bridge with a span arrangement of 41 m + 70 m + 41 m, 4 traffic lanes and a height-varying truss
It has been found that the preflex prestressing is suitable for this type of bridge and it has some advantages by comparison with conventional prestress, the Preflex prestressing technology of steel truss-concrete composite bridge (PPSC in short) was put forward on the basis of preflex prestressing method, the construction procedures are somehow different from that of used in continuous girder bridge, is worth writing a paper to demonstrate the feasibility and its advantages of PPSC technology on the one hand, and to describe the PPSC construction procedures in detail so that it can provide some references to the design of bridges of like on the other
In the conventional prestress method, the stress of the top chord and the bottom chord are small and mainly in compressive, under the pre-condition that at least 1 MPa compressive stress is reserved in deck panels under load effect combination, PPSC makes the maximum stress of top chord reaches 182 MPa, and maximum stress of bottom chord reaches 174 MPa, the maximum stress of steel tube bracket just increased from 119 MPa to 139 MPa
Summary
Guangdong Qingqiyong Bridge, crossing Qingqiyong River, is a prefabricated steel truss-concrete composite continuous rigid bridge with a span arrangement of 41 m + 70 m + 41 m, 4 traffic lanes and a height-varying truss. In this case, steel properties can’t be fully developed, but to meet the construction requirements, the cross section and plate thickness cannot be reduced further. It has been found that the preflex prestressing is suitable for this type of bridge and it has some advantages by comparison with conventional prestress, the Preflex prestressing technology of steel truss-concrete composite bridge (PPSC in short) was put forward on the basis of preflex prestressing method, the construction procedures are somehow different from that of used in continuous girder bridge, is worth writing a paper to demonstrate the feasibility and its advantages of PPSC technology on the one hand, and to describe the PPSC construction procedures in detail so that it can provide some references to the design of bridges of like on the other
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