Research On Construction Monitoring And Control Of Prestressed Concrete Continuous Bridge

Since the construction of prestressed concrete continuous bridges by cantilever casting method is a complex process, it is absolutely necessary to adopt monitoring and control measures in construction stages in order to ensure that both the alignment and loading conditions are coherent to the design requirements when the bridge is completed. Based on a cantilever cast three-span tapered continuous bridge, the actualization of monitoring and control and the alternation of alignment and stresses during construction stages are researched.First of all, with the analysis of the structure of the main bridge, according to the adaptive control theory, the detailed construction monitoring scheme is presented to satisfy the requirement of stability, deformation and stresses. Both stresses and alignment are monitored and the alignment is the key issue. Based on the newly applied design code JTG D62-2004, the bridge is modeled by FEM software. Several simplifications are made while simulating characteristics of steel and concrete as well as loading condition and boundary condition. Combined the forward-analysis method with the backward-analysis method, simulation of the whole construction process is carried out.Second, based on the actual construction monitoring data, the comparison analysis is made between the measured elevation record and the calculated result. Through sensitivity analysis, main design parameters are confirmed. Main parameters are instantly identified while the data difference becomes unacceptable, laying elevation is adjusted on the next stage to ensure the alignment is coherent to the design value and the closure can be finished successfully. Various load effects are analyzed separately by software in order to provide theoretical gist in identifying parameters while error occurs.Finally, the calculated stress data by two kinds of software(a spatial FEM software MIDAS/Civil and a plane bar-system FEM software) and the measured record are compared to make sure the stresses are within limit during construction stages. Results of the comparison show the advantage of spatial Finite Element software in modeling and analyzing.The successful completion and operation of the bridge indicate that the combination of the forward-analysis method and the backward-analysis method is appropriate in simulating construction process, the sensitivity analysis of the design parameters and the identification and adjustment of main parameters are necessary to diminish errors. Adaptive control method can be perfectly used in construction monitoring and control of prestressed concrete continuous bridge.