Design and Construction of Arch Bridge with Variable Steel-Concrete Composite Section Based on Vertical Erection-Rotation Method

摘要

This paper describes an innovative use of a variable steel-concrete composite section for the mainarch ribs to take combined advantages of steel and concrete strength. And vertical erection methodthat can significantly simplify and accelerate arch bridge construction with better structure integrityand higher stability during construction is proposed. Since steel construction is relatively simplebecause of its advantages of high strength to weight ratio, offsite prefabrication and quick on-thespotassembly, the use of steel box as the stiffening core of arch rib section becomes an ideal choicefor the initial arch framing using the developed erection method. The prefabricated steel box can beerected vertically on temporarily restrained horizontal hinge device at the spring line with minimalhoisting equipments. The completed two half-leaf can then rotate down on its own weight to meet atthe mid-span for closure in a few hours. The completed steel arch frame can serve as formwork andsupporting system to provide a sufficient and safe platform for the placement of concrete that formsa variable composite rib section, and for erection of spandrel columns and deck system. Thisconstruction technique and structure optimization can significantly simplify and speed up archbridge construction with added work zone safety and better constructability, thus provides a viablesolution for arch bridge construction having difficult site condition. Pilot projects including a 75-meter highway bridge are presented to demonstrate the basic concept, design features, constructionprocedures and erection control.