Advanced Materials Research Vols. 255-260

Abstract: Three kinds of subgrade soils with different plasticity index are selected from seasonally frozen soil region. Frost heaving ratio of volume and height was performed on the samples exposed to 0 to 8 times closed-system freeze-thaw cycles. The results show that concerning the same kind of soil, the frost heaving ratio increases with the number of freeze-thaw cycles; Frost heaving ratio increases with plasticity index under the same number of freeze-thaw cycles. Multiple nonlinear fitting is adopted for test data. The relationship between frost heaving ratio and plasticity index, freeze-thaw cycles is obtained and shows a good correlation. The relation can provide useful reference for subgrade design and construction in seasonally frozen soil region.

Abstract: In order to calculate the internal force of prefabricated skew-plate bridge (PSPB), the force state of PSPB with different skew angles is analyzed based on finite element technique. For the side slab, the value of load transverse influence lines of PSPB with different skew angles is obtained, at the same time, the relation between load transverse distribution coefficient and skew angle has been studied. Then a practical formula is derived according to the contrast curve. The comparison diagram of internal force between PSPB and main bridge with the same deck width is established, and a modified formula is deduced. This process provides a new idea on calculation of PSPB, and simplifies the design of PSPB.

Abstract: Steel and concrete composite girder began to be used in arch bridge. For the existing of shear lag, the concrete deck in same cross section did not bear identical stress completely. No stipulations for effective width of concrete deck of composite beam in arch bridge are given in current design specifications and codes, which causes difficulties in analyzing the mechanical behavior of composite arch bridge by beam-column method. In this paper, the mechanics calculation for a multi-span arch bridge with continuous composite beam is conducted. Stresses distribution pattern of concrete deck in transverse direction and the variation of effective width of concrete in longitudinal direction are studied. The degree of impact of effective width caused by varying loads on structure and by varying some details on structure is discussed.

Abstract: Reinforced concrete ribbed arch bridges are applied widely in China, especially in mountain areas of southwest China. After many years of operation, some distresses and damages occur of this kind of bridges. There are 100 bridges of this style are generally surveyed and 49 of them with typical distresses are investigated in details on site. Based on it, characteristics and rules of distresses are classified and summed up, and the reasons of them occurrence are analyzed. This process is expected to provide reference and evidence for design, construction, maintenance and strengthening of this kind of bridges, and establish a foundation for further research.

Abstract: The concrete decks in wide box composite girder bridge carrying vehicle load directly are easy to failure. So the decks in approach bridge of Jiubao Bridge are designed to renewable component. Several deck removal plans were put forward based on the structure characteristics of the Jiubao bridge. Spatial finite element model of the bridge was set up and the responses of approach bridge under different removal plan were analyzed. The analysis results show that methods proposed in this paper about deck removal in local position or in whole span are feasible; however different whole span removal method affect the mechanical behavior of the approach bridge heavily.

Abstract: The weakness of traditional dumbbell-shaped section is that when concrete is filled into the web space, great stress is likely to produce cracks in the weld sealing between steel tube and web plates. In order to avoid this condition, a new-type dumbbell-shaped section is proposed. Experiments on concrete filled steel tubular (CFST) model arches with new-type dumbbell-shaped section have been carried out, concentrated loading at crown and L/4 section respectively. The result indicated that the new-type CFST arch has good elastic-plastic behavior and high strength, no local buckling appeared during the whole loading process, its in-plane mechanic behavior is similar with that of the CFST arch with single-tube. The dual nonlinear finite element calculation model is set up for the model arch, by means of this model the load-deflection curves during the loading process and the ultimate load-carrying capacity is analyzed.

Abstract: Based on improved linear regression filter method presented by Iwatani and wind tunnel test data, the program simulated 3-D time history of fluctuating wind pressure of Fuzhou Strait International Conference and Exhibition Center considering spatial correlation of wind loads, which is consistent with the object power spectrum .The simulation result is used in nodes of the structure to analyze response of wind-induced vibration. Analytical results show it has the maximum displacement response in 0° wind direction .Due to the installation of TMD, node displacement response of roof truss is reduced from 44.14mm to 33.16mm, with best reduction 26.67%.

Abstract: Anti-slipping safety factor between the main cable and saddle, deflection-to-span ratio of main girder and force in the mid-tower, which are not important factors in two-tower suspension bridge design, yet becoming dominant ones in three-tower. Moreover, these factors are all controlled by live load. Thus geometrical nonlinearity under live load for three-tower suspension bridge becomes even more significant. This paper takes Taizhou Yangtze River Bridge as the study object, and uses linear deflection theory, incremental UL formulation and total CR formulation to study the geometrical nonlinearity of various key responses of the structure under live load. It is concluded that accuracy and efficiency of total CR formulation is the highest among the three as well as the maximum error of incremental UL formulation is no more than 0.3%; however, the error of widely used linear deflection theory is 6.6%, 4.5% and -2.64% respectively, which is conservative and can not meet the requirements of sophisticated analysis.

Abstract: The seismic behavior research of Fengdu Bridge with nonlinear viscous dampers will be conducted to investigate two parameters of damping coefficient C and damping exponent ξ through nonlinear dynamic time-history analysis. Simultaneously, the analysis results are compared with the seismic response without viscous dampers and proposed control methods and formulas of a reasonable selecting damping coefficient C and damping exponent ξ are provided. The parameters sensitivity study indicates that setting dampers in longitudinal direction of bridge can reduce the relative displacement of key positions and the response of the bridge, the beneficial effect of the isolation in the longitudinal direction, but important amplification occurs in the vertical direction for relatively high frequency components. Moreover, the reference of application of nonlinear viscous damper will be provided for similar projects.

Abstract: This paper intended to determine the influence line for structural members in a Chain Suspension Stiffening Beam Bridge (CSSBB). In an engineering case, flexibility method determined the redundant bar force in CSSBB as the unit live load stayed at different positions on the main bridge beam. These calculated redundant bar forces composed the influence line. The foregoing flexibility method considers suspenders deformation. Results indicate that redundant bar force is maximal when the unit live load stays at the main beam midpoint in Figure 2. The redundant bar force in Figure 3 is the actual force in bar 3 in the actual structure in Figure 2. The redundant bar forces and internal load equilibrium equations can determine the influence lines for other structural members. Simple-supported Beam Bridge (SSBB) can be constructed easily while and wire (cable) suspension bridge are suitable when the bridge is to cross a wide river. CSSBB and arch bridge demonstrates less deflection and less moment at the beam midpoint than the SSBB.