Applied Mechanics and Materials Vols. 405-408

Abstract: Post-prestressed duct grouting is a complex construction process and it is affected by many factors. Since there are no clear cognitive relations to the influencing factors of the grouting quality, it is hard to make the best control program during the construction. By the theoretical applicability and parameters analysis through the grouting process, this article used the numerical simulation method to analyze the grouting process and obtained the correspondence between the initial velocity, grouting pressure and grouting quality. To the height difference and bending in the duct, the relationship between volume and forming quality were analyzed, the results has reference value to the design of duct gas vent.

Abstract: The running performance of train on Hubian bridge was analyzed with energy random analysis theory for derailment. The calculated result shows that the running safety of train cannot be ensured with the existing operation condition, and the measurement of rate-limiting or reinforcement is needed to be taken for this bridge. A method for establishing index of traffic safety for railway bridge was proposed. The detailed contents of the method are as follows. The lateral amplitude on the middle of beam is determined as index for traffic safety for beam-pier system. The critical beam-pier system with which the running performance of train can be guaranteed is determined. The lateral amplitude of critical beam-pier system is calculated and determined as limit value for traffic safety. The limit value of lateral amplitude for traffic safety for Hubian bridge is determined as L/6400.

Abstract: Euler beam dynamic analysis model under moving loads and wheels plus spring-damper-sprung mass action were established respectively. The simply-supported beam motion control equations were derived and the corresponding simulation analysis procedures were worked out. The vertical dynamic responses of simply-supported bridge under typical vehicles at different speeds were studied systematically. Impact factors calculated from the two analysis model were compared with the values of the current bridge specifications. It is shown that vehicle inertia force has little effect on the vertical deflection and vertical vibration acceleration of the bridge, the vehicle impact effect on bridge gradually go up with the passing speed increasing, vehicle weight has great influence on the vertical vibration of the bridge. The problem of passing overloaded vehicles must be considered seriously in bridge design and use.

Abstract: The frequency method is an indirect method of measuring cable tension, in which using the relation between vibration frequency and cable tension, and measured frequency. It has been found wide use because of its simplicity, practicable use, higher accuracy and the instrument is easy to carry. The principle of the frequency method is based on the vibration theory of string or beam. The flexural rigidity of cable is ignored in string vibration theory, but included in beam vibration theory; therefore the latter is more approaching the engineering practice.

Abstract: At present, China's large span continuous rigid frame bridge (CRFB) has made rapid development, and has been applied in the railway bridges. This paper based on finite element analysis software ANSYS, using the simplified algorithm, establish a line - bridge - pier integration model for calculation of continuous welded rail (CWR) on bridge, the continuous rigid bridge and continuous rigid frame bridge (CGB) in two different conditions were compared and analyzed. The calculation results show that: the rail expansion force, bending force, braking force, rail broken gap of CRFB are smaller than that of the CGB of same beam span, in CWR, CRFB has obvious advantages, it should be popularized.; equivalent temperature span of CRFB are smaller than that of the CGB of same beam span, so the CRFB is less affected by the temperature; because of the pier and girder consolidation of CRFB, favorable to CWR, but due to the bending effect of bridge piers can lead to beam produces larger vertical deformation, thus affecting the track smoothness, which must be noticed in design.

Abstract: The paper is focused on the problems of the actual fatigue resistance of assembly joints of the temporary footbridge, which is newly developed in the authors workplace. The necessity of the development of a new temporary footbridge has been invoked by the lack of such constructions in a practice, both in the case of flood situations, and also as the site facilities. Within this work the attention is paid to static and structural design, mainly to the harmonization of both aspects, to achieve the efficient design. In parallel, two types of the footbridge are developed, both ones with a lower deck, truss main girders and bracings. The first structure short footbridge can reach up to 18 m span; the second structure long footbridge reaches up to 36 m span. This paper deals with some problems of the short footbridge fatigue and presents the basic information on the actual behaviour of assembly joints of the structure in the case of fatigue loading actions. The paper is focused on the fatigue tests of assembly joints including elaboration and evaluation of their main results.

Abstract: Due to the small section dimension, high compressive strength, large stiffness, and excellent deformation capacity, the use of concrete filled steel tube (CFST) piers is attractive, especially to high-pier and super-high-pier bridges located in mountains. This paper reviews available information concerning the application and development of CFST piers. Three bridge examples are then introduced, while the structural design and the construction methods of CFST column piers are described in detail. Furthermore, main parameters of CFST piers, such as slenderness ratio and material strength are concluded. Finally the future research direction of CFST column piers is viewed.

Abstract: Masonry arch bridges with unequal spans are outstanding kinds of masonry bridges which are widespread in historic countries spatially in Iran. The differences in dimension of arches which mostly lead to formation of curve shaped decks in such bridges, brings a particular architecture for masonry arch bridge. However the elements which bring different lengths and heights for spans have not yet been studied. In this research by geometrical and structural survey on Khan Bridge, a kind of multi unequal span bridge in south west of Iran, it is demonstrated that especial conditions of the case lead to formation of its architecture. It is illustrated that shape of river bed, hydraulic and geotectonic factors and structural stability, are of paramount importance in terms of featuring the architecture of multi unequal span bridges with curve shaped deck.

Abstract: Atmospheric underlying surface change is the main reason for urban heat island and fog and haze. According to constructing a network-like cold bridge as well as coordinating the layout of urban hard underlying surface and soft underlying surface which can promote urban wind-heat movement, urban thermal climate environment may be improved by diffusing heat and solids effectively. As to suzhou, both city regional natural ecological pattern and main urban areal natural ecological environment structure reflect this philosophy.

Abstract: In order to research on mechanical properties of flexible suspension bridges, a geometric nonlinear analysis method was used to simulate on the experimental results, and carried on static loading test finally. In the loading test process, the deformations were measured in critical section of the suspension bridge, and displacement values of measured are compared with simulation values of the finite element simulation. Meanwhile the deformations of the main cable sag are observed under classification loading, the results show that the main cable sag increment is basically linear relationship with the increment of mid-span loading and tension from 3L/8 and 5L/8 to L/2 section, the main cable that increasing unit sag required mid-span loads and tension are gradually reduce in near L/4 and 3L/4 sections and gradually increase in near L/8 and 7L/8 sections and almost equal in near L/2, 3L/8 and 5L/8 sections. From the experimental results, the flexible suspension bridge possess good mechanical properties.