Study For Dynamic Unstrained Geometry FEA And Construction Control Of The Reinforced Concrete Arch Bridge With Vertical Rotation From Above To Below Method

For the undeveloped economy, inadequate transport facilities and mountainous terrain in China’s western mountains, most bridges need to across the deep V-shaped ravine which is the direct cause of the construction difficulty. Based on the above circumstances, the reinforced concrete deck arch bridge has obvious advantages compared to the other bridges. Therefore, it has practical significance to study the new construction technology of the reinforced concrete arch bridge that across the canyon in mountains area. When there is no prefabrication site around the construction site of the reinforced concrete arch bridge or it is difficult to transport the prefabricated members, it is economically to construct the arch ring with the negative angle vertical rotating method, which aslo has the unique advantages such as convinient installation, good structural intergrity, less and easy maintenance.It is the first time to apply the negative angle vertical rotation construction technology to the reinforced concrete arch bridge in China. Taking Pearl Bridge as an example, and on the basis of the related information collected and in-depth analysis at home and abroad, this paper conducts the following researchs with regard to the existing problems of this subject.(1) The finite element analysis based on the dynamic unstrained geometry is put forward, which provides a new idea for the simulation of the bridge construction process. The tension and compression link element with gaps based on the dynamic unstressed length is put forward to simulate the mechanical behavior of the bolted structures with gaps, the cable element and truss element based on the dynamic unstressed length are put forward to make it more convinient to simulate the tensioning construction of the cable. In order to improve the computational efficiency of the bridge construction process simulation and to ensure the accuracy of calculation, this paper adopts the different solution strategies for different structural mechanics model and puts forward the iterative method based on the remaining load coefficient increment theory for part of the no-linear caculation.(2) This paper establishes a DUFE programe to apply for calculation of bridge construction. This program not only can solve the caculation problem of the negative angle Vertical Rotating Construction of the reinforced concrete arch bridge, but also can solve the caculation problems of other types of bridge such as the stay-cable bridge, suspension bridge, continous beam bridge as well ascontinous rigid frame bridge. The accuracy, reliability and practicability of the finite element computational program based on the dynamic unstressed length in this paper is verified by analyzing the classic validation example of the finite elment program and the instance example of the reinforced concrete arch bridge construction process.(3) This paper studies the key technology during the negative angle vertical rotation construction process and determination of axis linear. In each negative angle vertical rotation construction stage of the arch rib, taking the arch axis linear as the research object to study the completed bridge arch axis linear, the unstressed arch axis linear, the casting arch axis linear and the templet installation coordinate in sequence with the step-by-step algorithm. Study the method of determining the rotation stayed-bukle cable force and the pulling cable force in the traction stage. Adopt the stress balance method and introduce the iterative algorithm to determine the adjustment range of the cable force. Conduct the optimization calculation for the closure process of the stiff skeleton after the arch rib is rotated in place. The optimal removal scheme of the rotation stayed-bukle cable and the temporary tie bar is proposed after the stiff skeleton is closed. Take the Pearl Bridge as the example to design the key structures that are needed when construct the reinforced concrete arch bridge with the negative angle vertical rotation method, which can provide reference for the similar engineering design.(4) It analyzes the sources and types of errors during the negative angle vertical rotating construction of concrete arch bridge and the ways to reduce errors are also proposed on basis of studying the related information collected and researchs at home and abroad. In order to reduce the control errors in the construction process of the reinforced concrete arch bridge with the negative angle vertical rotation construction method, it adopts different kinds of control method to conduct the sensitive analysis of the construction error parameters that is caused in the negative angle vertical rotaion constructon of the Pearl Bridge, and establishes a set of construction control system for the negative angle vertical rotation construction of the reinforced concrete arch bridge.(5) it analyzes the negative angle vertical rotation construction of Pearl Bridge based on the dynamic unstrained geometry FEA. And coMParison with the actual on-site construction monitoring data is conducted. Besides, it also analyzes the cause of difference between theoretical results and the actual monitoring results as for displacement of the arch, temporary traction cable force and stress of key cross section of arch, in addition, it summarizes the ways to minimize the difference which can be referenced for construction monitoring of similar bridges.