Applied Mechanics and Materials Vols. 256-259

Abstract: The non-navigable arch bridges of Hong Kong-Zhuhai-Macao Bridge use embedded prefabricated pile foundation. According to the technology difficulties of pre-fabricated abutment and pier lifting construction under marine environment, A kind of suspension system with hoisting and positioning function is put forward and designed, of which the structure and working method were introduced in this paper.

Abstract: The crack in inclined web of the prestressed concrete continuous girder bridge which is constracted by the way of cast-in-place cantilever method that become one problem that should be more cared about[1-2]. This paper analysis the bridge in three different conditions which are according to the pratical and special engineering to find the causes of the formation of crack in inclined web of prestressed concrete continuous girder bridge in cantilever construction. The results of the analysis show that the additional stress caused by the different temperatures between internal and external components leads to the formation of the crack in inclined web of the bridge.

Abstract: A numerical model was established for a continuous beam bridge with FPS bearings. It started from Lagrange equation in dynamic mechanics. The software for its numerical solution was presented with Newmark-β method. Computation results show that efficiency of the seismic isolation system is closely related to slipping friction factor on the contacting surface and slide radius. The internal forces (shear forces) for piers exhibit a significant reduction under an optimum combination of friction factor and slide radius. For friction factor being in the range of 0.1-0.2 and slide radius 1.5m, the shear force could be decreased by more than 50%, and the drift of beam would be less than 2cm in horizontal direction and less than 0.1cm in vertical direction respectively.

Abstract: In view of the modal parameter identification when only has the output signals of the system under ambient excitations has difficulty, a new method which can identify the structural modal parameters exactly based on singular value decomposition of the power spectrum is put forward. This method is used in the modal parameter identification of a cable stayed bridge under ambient excitations, and the identification frequency is compared with the finite element computation frequency. The results indicated that this method has overcome the subjectivity in modal selection of frequency domain pick-peaking method, choose eigenfrequency and identify close modal accurately and objectively. With the advantages of practical, processing simply and fast.

Abstract: Based on the Taizhou Yangtze River Bridge, a 3D finite element model is developed to establish its deformed equlibrium configuration due to dead loading. Strating from deformed configuration,a modal analysis is performed to provide the frequencies and mode shapes. The study focuses on the effects of the vertical, lateral and torsional stiffness of the steel box girder, the rigid central buckle and the elastic restraints connecting the towers and the steel box girder on the dynamic characteristics of the triple-tower suspension bridge. The results show that, variation of vertical, lateral and torsion stiffness of stiffening girders have effects on the vibration frequency in corresponding directions only and have little effects in other directions. The elastic restraints have a more significant effect on the dynamic characteristics than the central buckle, and decreasing the stiffness of the elastic restraints results in the appearance of a longitudinal floating vibration mode of the bridge. The results obtained could serve as a valuable numerical reference for analyzing and designing super-long-span tripletower suspension bridges.

Abstract: When stimulate temperature field of concrete box girder caused by solar radiation with ANSYS, it’s feasible to turn boundary conditions to third boundary condition. Taking Ping'an Huangshui River Super-large Bridge in Qinghai Province for example, the research analyzes box girder temperature field distribution and deduces realistic temperature gradient mode by comparing calculations with measurements. Calculations show that bottom slab of box girder also has quite big temperature gradient which should be taken seriously in bridge structure design.

Abstract: The seismic behavior of concrete-filled circular steel bridge piers was studied by testing four large scale models which were subjected to a constant axial load in addition to a cyclic lateral load. It was found that concrete-filled circular steel bridge piers had high ductility and energy dissipation capacity. Based on the hysteretic force-displacement, the hysteretic behavior of strength reduction was analyzed. Based on the axial strain and the circumferential strain, the plastic area and the strain feature of steel tube were analyzed. According to two different constitutive models of concrete-filled steel tube, the skeleton curve of moment-curvature and force-displacement were calculated and compared with testing data.

Abstract: Nakamura’s model is one of the most practical models describing the lateral vibrations of footbridges induced by pedestrians. This paper presents a calculation of the periodic solution in Nakamura’s model. After a Hopf bifurcation analysis of Nakamura’s model, the amplitude of the lateral vibration is computed by using the energy method. The correctness and accuracy of the calculation is demonstrated by numerical simulations. Then, how the factors and variables in Nakamura’s model effect the amplitude is investigated based on the analytic solution. Our analysis results may be used to explain why the most of the predict results of Nakamura’s model are larger than the measure data.

Abstract: Targeted at key technological difficulties of pre-stressed concrete bridge with precast segment assembling in short-line matching method, combined with the as-built projects and those under construction, this essay introduces systematic segmental precast assembly externally prestressed concrete construction technology in short-line matching method, and the developed serial complete equipments set, thus realizing development trend of factory-orientation, large-scale, mechanization, standardization of modern bridge construction.

Abstract: The principle and procedure of bi-directional evolutionary structural optimization (BESO) are stated in detail. A program based on BESO is introduced in conceptual bridge design. Topology optimizations are achieved for deck arch bridges with different rise-to-span ratios, half-through arch bridge, through tied arch bridge, bridge pier and bridge main beam. The results demonstrate rational structures with well-distributed stress and smooth force transmission, which indicates the efficient of the method.