In this paper,the crack width of continuous steel-concrete composite beams in the negative bending area is researched by the way of theoretical and experimental analysis.

According to the basic theory of two-dimensional unstable temperature field,considerig the third condition to solve the differential equation of heat conduction as temperature load,the sunshine-induced time-varying temperature distribution on the cross section of a real bridge s steel-concrete composite beam was simulated using ANSYS.

The article introduces the structural design of steel-concrete composite beam of the main bridge of Zengbu Bridge in Gunagzhou City,calculates the structure of the main bridge,discusses the construction scheme of the main bridge and the foundation treatment of old bridge sunk well, and focuses on the analysis of the structural design and construction points and difficulties of the main bridge.

It has a main span of 360 m I steel concrete composite girder and side spans of 144 m prestressed concrete beam each.

The rebuilding scheme fully considers the harmony of the whole bridge with the surrounding environment, meets the planned traffic function requirements and the relative technical standards, puts forward the design of the steel composite beam structure for the main bridge and the technical measures taken for the sunk shaft foundation treat.