Applied Mechanics and Materials Vols. 501-504

Abstract: In order to make the damaged bridges continue to play a role in a short period of time, ensure the normal order of the bridge structure is used,and ensure the traffic safety, we carried out the bridge reinforcement and repair work. On the basis of the actual testing data in combination with the practical situation of engineering and the damage degree, we damaged parts of the bridge of grouting reinforcement, embedded, anti-corrosion treatment, eliminate the hidden trouble of the structures, to guarantee the normal operation of city traffic. This article mainly introduces the harm of main girder section and the reinforced repair way.

Abstract: Currently the bridge structure detections are mainly based on static load test and dynamic load test. The static load test has shortcomings of less test data, long time-consumption and high cost. However, the dynamic load test has the advantages of quick and convenient, its related technologies and theories are still not mature enough. To solve this problem, the detection of bridge structure based on quasi-static test is proposed in this paper. Quasi-static load is applied on the structure by moving the standard load vehicle slowly. Then create the structural finite element model and modify the model according to the measured data to make it consistent with the actual structure. The bridge actual structural mechanical properties can be acquired by conducting load test on the optimized structural finite element model. By doing this, the bridge safety could be evaluated quickly.

Abstract: We analyze existing masonry arch-bridges and corresponding reinforcement methods in this paper and bring about the method of using strip-shaped outer-wrap reinforced concrete with chemically planted bar to improve the new and old concretes cooperative work so as to strengthen the wholeness and improve impermeability of the bridge. We also compare two experiments on one actual bridge of 30 cm strip-shaped outer-wrap reinforced concrete in the main arch ring and 20 cm global outer-wrap reinforcement concrete, of which the data shows the superiority of strip-shaped outer-wrap reinforced concrete for it strengthens both the bridge floor and bottom structure and improve the load capacity.

Abstract: The train-bridge aerodynamic spatial model was established, and the aerodynamic coefficients of train on bridge were calculated accordingly. The method for acquiring train critical speed under crosswind was derived by the statics, the displacement bring from springs, aerodynamic force, lateral and vertical vibrational inertia force, centrifugal force and gravitational force were considered in the derivation. The results show that the head trains aerodynamic coefficient will reach peak value around wind incidence angle, the rear trains aerodynamic coefficient varies constantly with incidence angle. Side force and lift force coefficients will get maximums when train attack angle , overturning moment coefficient absolute get maximum at . For trains overturning stability, crosswind from the inner of curve blows to the head train running on the windward line of bridge is the most dangerous situation.

Abstract: Based on fuzzy decision theory, multi objective fuzzy optimization is done for the dynamic isolation model scheme of self-anchored cable-stayed suspension bridge. Using two comparison theory solves the problem of quantifying the qualitative indexes and distinguish the concepts of importance and superiority. Combining the fuzzy decision method with engineering practice and using the results of five cases are proposed for multi objective fuzzy optimization. Comparison results show that it is more reasonable to place lead rubber bearings not only between pier and girder, but also main tower and girder, with viscous dampers between main tower and girder on the same time. This method can provide a reference for structure selection in practical conceptual design phase.

Abstract: The distributed properties of residual stress in bridge nodes have been investigated in the paper. Based on some bridge node, the three dimensional thermodynamics finite element model has been established, meanwhile, the double ellipsoidal distributed heat source model are used to simulate the whole welding procedure of bridge nodes according to the welding parameters. Thus, the distributed regularities of residual stress of bridge node have been obtained. Simulating results show that the residual stresses distribute uniformly in the welding direction, and the max value reaches the yield strength of steel Q345qD. Besides, the residual stress in the lateral direction reaches the max value in the place of welding district, and decreases rapidly when far away from the welds.

Abstract: The extradosed cable-stayed bridge is a new type of bridge developed in recent year. The optimization methods commonly used are based on the cable-stayed bridge and not entirely suit for the extradosed cable-stayed bridge. The paper puts forward a new optimization method, which applies the unknown coefficient functions aided by MIDAS/CIVIL, it takes the reasonable feasible range of dead moment solved by stress balanced method as the constraint condition, makes the square of unknown coefficients as objective function, and solves the cable force based on the effect matrix method thus to determine the cable force in reasonably completion state. This new method is verified with favorable effect, the internal force of this structure appear significant improvement. And finally, the results show better cable force obtained under the method in this paper compared with the cable force under other constraint conditions and objective functions.

Abstract: The stayed cable is the key part of the cable-stayed bridge and the main bearing section. Stay cables are prone to vibration under the loads of the rains winds, earthquakes and transportation for the long-span bridge is very flexible and the damping is small. A long time effect of cable vibration on the structure durability has become a serious problem of cable-stayed bridge in the development and operation. Wind induced vibration of stay cable shape is analyzed, and some common damping measures are expounded in the article and it provides the basis for further study in the future.

Abstract: This paper examines the bearing capacity and stability of a catenary axis uniform cross-section multi-span stone arch bridge with solid spandrels in the cold areas. Taking the West Ulanhot Large Bridge built in cold area of Inner Mongolia in 1960s as an example, the bearing capacity and stability of early-built stone arch bridge were calculated,in consideration with the effect of dead load, live load and temperature variation as well as multi-arch action on the main arch ring, in the light of current specification, i.e., the Code for Design of Highway Masonry Bridges and Culverts (JTG D61-2005) published by the Ministry of Communications of the People's Republic of China. The aim was to evaluate the safety of the old multi-span arch bridge through the theoretical analysis and checking calculation based on the current specification.

Abstract: This paper presents a survey of construction techniques for pre-stressed concrete (PC) box-girder bridge with corrugated steel webs in recent decades. The structural forms of the bridge have experienced simply supported beam bridge, continuous girder bridge, cable-stayed bridge and the continuous rigid frame bridge. Meanwhile, the construction technologies were constantly innovated, including cast-in-situ, precast and the combination of them. The processing and installation technologies of corrugated steel webs and several typical construction techniques for PC box-girder with corrugated steel webs were elaborated, such as full framing construction, cantilever construction, span-by-span construction, incremental launching construction and some other various innovative ways. The valuable experiences in a variety of construction methods were summed up. The results show that some innovative construction ways should be developed by fully utilizing the corrugated steel webs as a guide beam or a work platform to improve the efficiency of construction.