Advanced Materials Research Vols. 255-260

Abstract: There is a deviation between finished bridge and design requirement of prestressed concrete (PC) cable-stayed bridge due to the construction errors in construction process. Besides, the randomness of construction errors will cause the variability of structure system in construction state. However, the most common analyses considering construction errors are based on deterministic analysis method, which concern the mean errors effect merely. These are inadequate obviously. In this paper the main construction errors of PC cable-stayed bridge and corresponding distributions are outlined firstly. Also several common stochastic analysis methods are introduced. Using Monte-Carlo method with ANSYS finite element analysis (FEA) software, then, a stochastic analysis of a single tower PC cable-stayed bridge considering construction errors is completed, and the probability characteristics of structural response under dead load are obtained. Finally, from the reliability point of view, the influence of randomness of construction errors on structural safety and the necessity of stochastic analysis for PC cable-stayed bridges are discussed.

Abstract: The damage of bearing will change the boundary condition for whole bridge, if we do not take account of bearing failure, the error of structural analysis and the unreasonable in design will be made. In this paper, the effect of possible bearing damage to whole bridge during strong ground motion is studied through examining the seismic performance of a multi-span continuous girder bridge which is a real damaged bridge during the Wenchuan earthquake in 2008. Proper analytical restoring force models of bearings are proposed, which can simulate the seismic performance of the bridge before and after the bearing damage suitably.

Abstract: Reduction of intensity or rigidity and losses of quality of the bridge structures can induce the changes of modal parameters of the structure. It is possible to analyze and detect the damage of bridge based on comparing the changes of modal parameters of the structure before and after damaging. Natural frequency, displacement mode and modal curvature are the important parameters in dynamic Analysis. In this paper, their adaptive capacities to bridge damage assessment are discussed. And the damage factor is used to determine the damage location. Model experiments show that the damage factor not only reflects the position of bridge damage, and the damage factor of some vibration mode also indicates the length of damage element. At the equilibrium position of the vibration mode, it is difficult to determine structural damage using the damage factor.

Abstract: The paper studye the cable deflections of cable-stayed suspension bridge subject to living load. in addition, an analytical formula of the gravity stiffness of the cable-stayed suspension bridge is derived. Duo to the dead load state in the cable-stayed part is more differ from that in the suspension part, the research aim at different parts of the cable in the cable-stayed suspension bridge. Using the energy relation principle associated with deformation of the cable, the cable deflections and gravity stiffness of cable-stayed suspension bridge are derived.

Abstract: The construction scheme of long-span V-shape rigid frame composite arch bridge is discussed. In process of simulation calculation of the construction, the author compiles APDL command flow program by using the unit birth-death technique, establishes simulation calculation model in the construction process. The creep characteristics of concrete are also taken into account. The whole process of beam first-to-arch later stage construction are calculated and studied.By researching on construction control of Xiaolan channel super large bridge, the feasibility of the construction program is evaluated, the alignment and displacement in each construction ideal state are determined and the alignment and displacement in the following construction state are predicted. The stress controling results of the critical sections are researched on to make the construction go along well as designed, make sure the safety during construction, the structural internal force under constant load and structural alignment are complied with the design requirements and the construction quality and safety are ensured.

Abstract: This paper presents the rehabilitation project of Dabanshan highland road tunnel. Cause analysis is carried by insight into the information of climate, geological, hydrological condition, tunnel defects type and parameters. Water leakage, low temperature and poor rock condition are considered to be source of tunnel defects, and the essential of rehabilitation of highland road tunnel are water leakage treatment and heat preservation system reinstatement. Measures taken to solve the problems of cracks, water leakage and frost are introduced in detail, and results show that measures taken are proved to be effective. Knowledge and experience gained are helpful for similar projects in future.

Abstract: Taking deformation of the main arch under dead load as the arch alignment control target, the overall cable force and pre-camber of multi-rib arch were calculated by zero-order optimization method. According to the installation sequences of arch segments, taking deviation of cable tower, cables in one-time tensioning method and the section stress of arch chords as constraint conditions, the cable force and pre-camber for every segment were calculated by iterative method. This method is applied to the erection of a 400m steel truss arch bridge with three ribs, the calculated values of cable force are anastomosed with the measured ones, and the precision of arch alignment is high.

Abstract: Aiming at 195m high single pier of Hezhang Bridge, elasto-plastic stability analysis on static wind loads and temperature gradients at the longest cantilevered stage for single pier has been performed by ANSYS software. To overcome the problem on buckling of main girder ahead of piers, a loading way with concentrated force instead of uniform load was presented. A general expression of beam element-based temperature distribution along pier was given. Stability analysis under three different actions of wind load at the longest cantilevered stage was conducted according to Chinese Wind-resistent Design Specification for Highway Bridges. The results show that whatever static wind load or thermal gradient effect is, the inelastic stability factors against buckling are all over 3.0 and satisfy the engineering requirement.

Abstract: A new chorded arch bridge is put forward by Professor Zhixiang zhou of Chongqing Jiaotong University. For further exploration by the bridge design and construction scheme of the feasibility and rationality, and to verify the correctness of the theoretical analysis and probe the effective measures to deal with the closure error during in the rotating construction, a model made with by organic glass (ratio of the model to original bridge is 1/10) is has been experimented. In this test, the rotating down procedure of the construction was simulated and studied, possible closure errors were tested and corresponding measures are proposed, and the mechanical performances at key stages of construction and service were examined. Plentiful experimental data and some new knowledge about the chorded arch bridge were obtained from this test, which provided reliable technical guarantee for the actual construction.

Abstract: The Anqing Changjiang River Railway Bridge is an important fixed link across the Changjiang River in Anqing both the Nanjing-Anqing Intercity Railway and Fuyang-Jingdezhen Railway. Its main bridge is a six-span continuous steel truss girder cable-stayed bridge with main span of 580 m. The purpose of this paper is to describe some of its main features and FE model for geometrical nonlinearity using the finite element program ANSYS as well as control method of stress-free status for erection of cable-stayed bridge. Based on geometrical nonlinear analysis theories, secondary development of ANSYS using APDL was accomplished.