Research On Static And Dynamic Detection Method Of Simple Supported-continuous Box Girder Bridge

The construction sequence of simple supported-continuous box girder bridge is as follows: first, set the precast main beams in place, forming the state of simple supported bridge; then cast concrete in a certain range of both sides of the pier cap, and place the short prestressing tendon in the main beams to realize continuation. The construction of simple supported-continuous box girder bridge is simple and feasible, which needs little input of construction material and equipment. The short period of this construction method is easy to realize the prefabricated construction and standardized construction. The prestressing tendon at the wet joints, make the bridge have better continuity and integrity. Compared with the prestressed concrete continuous beam bridges, this kind of bridges have many advantages,such as low cost. Therefore, the simple supported-continuous box girder bridge is widely used in the small span prestressed concrete continuous beam bridge construction.The cognition people have on the the simple supported and continuous beam bridges is far more profound than on the simple supported-continuous box girder bridge. To abundantly master the mechanics characteristics of this kind of bridge, conducting on-site tests to obtain firsthand test data is very necessary.Nowadays, bridge detection methods can be generally divided into three categories—visual examination and nondestructive detection, static load test and dynamic load test. Visual examination and nondestructive detection evaluate the bridge service property by combining the damage extent identified by appearance observation and the nondestructive detection data. Because of the strong subjective factors, this kind of detection method can't exactly evaluate the bridge service conditions. Static load test uses the static responses under specific test load to evaluate the service conditions of the bridge under static load. And the dynamic load test evaluates the bridge dynamic behaviour according to the dynamic response and dynamical parameters. The bridge service condition evaluation of the static load test and the dynamic load test are both based on the bridge mechanical parameters, so their assessment results are all reliable.At present, the integrated and systematic static and dynamic load test methods of the simple supported-continuous box girder bridges are not formed. Thus, it's very meaningful to research the static and dynamic load test methods of bridges.This paper first concludes the fundamentals of solving the structural static and dynamic properties by finite element method, and then establishes the solid finite element analysis model of the simple supported-continuous box girder bridges based on grillage simulation. The static and dynamic load test programs are designed and The tests, based on the static and dynamic load test programs designed, are conducted for the Dongrong Bridge in changchun. According to the test results, the service conditions of the bridge are assessed. This paper generally conducts the researches as follows:1. This chapter concludes the fundamentals of solving the structural static and dynamic properties by finite element method, based on which the general process of establishing the theoretical calculation model by grillage simulation of simple supported-continuous box girder bridges is presented. At last, the grillage model of Chuanchun Dongrong Bridge is established for calculating the static and dynamic properties.2. In this chapter, according to the force characteristics and based on the established theoretical calculation model, the static load test programs of Chuanchun Dongrong Bridge are designed. According to these programs, static load test is conducted and static responses of specific sections are obtained. Based on the static response data, it analyses the rigidity, strength and the transverse load distribution.3. Based on the beam grillage model, the dynamic properties are analysed. According to the analysis results and the characteristics of the simple supported-continuous box girder bridges, the dynamic load test programs for Chuanchun Dongrong Bridge are established to collect the acceleration time history response. Then the dynamical parameters are identified by combining Random Decrement Technology and ITD. At last, according to the identified dynamical parameters, the service conditions of Chuanchun Dongrong Bridge are evaluated.