Xiao Rucheng

Damage identification of a large-span concrete cable-stayed bridge based on genetic algorithm

The global stability of a structure, the stiffness of its main girder and concrete tower, and the variation of the forces of its stay cables are key issues to the safety assessment of an in-service cable-stayed bridge. The efficiency and rationality of local elaborate non-damage-identification could be enhanced by the primary damage identification of cable-stayed bridges on the basis of periodic detection of the cable force and strain monitor in key sections of the main girder. The genetic algorithms of damage identification for cable-stayed bridges were investigated in this paper on the basis of the monitor data of the cable force and strain in a key section of the main girder. A damage detection program for complex civil structure was generated to implement the identification of damage location and extent. The deterioration of the structure was calculated according to the variation of monitor data. It is demonstrated that the results of damage identification from the parametric finite element method are accurate. The method had been verified using a long-span concrete cable-stayed bridge in Ningbo, which has been in use for the past four years.

Analysis of the cause of bursting on bottom slab of long span prestrssed concrete box girder bridge

Based on an accident of bursting and crack of bottom slab of one continuous box girder bridge during construction, the damage mechanism was analyzed using spatial finite element method. Parameter analysis on main factors influencing the vertical stress state of bottom slab of cantilever casting prestressed box girder segment closure and nearby segment was carried out. Then stability performance of box girder segments with cracked bottom slab were studied. It is concluded that radial force of bending prestressing strand and additional radial force with its deviation from the design position were the main reasons for bursting cracks in box girder bottom slabs, and the final failure form of bottom slabs was unstable destruction.

Research of the Dynamic Behavior of Long Span Suspension Bridges Under Static Wind Load

The dynamic behavior of long span suspension bridge is the key to the research of its windinduced vibration and seismic response. Since suspension bridge is a type of geometrical non\|linear structure,its dynamic behavior is closely related to the inner force state.The static wind load would thoroughly change the inner force state of the structure, and consequently change the dynamic behavior.In this paper we explore the influence on the long span suspension bridge by static wind load and put forward our calculation method of the dynamic behavior of long span suspension bridge under static wind load.