Advanced Engineering Forum Vol. 5

Abstract: A computer simulation method of solving vehicle-bridge system vibration response considering wind load is presented based on mode integration theory. Vehicle model and fluctuating wind load model are established, corresponding vehicle stiffness and damping matrix is educed in the method. A practical cable-stayed bridge dynamic analysis is completed successfully by programming with fore mentioned method. Wind load have a great influence on bridge vibration acceleration under low wind velocity. Vehicle vertical dynamic response is influenced evidently by wind induced bridge vibration, its lateral response is controlled by wind load and bridge response. The effect on system dynamic response of wind load is remarkable. For other type large span bridges the method also can be referred and have important application value in interrelated research. The accuracy of calculation is high enough for practical purposes.

Abstract: With good stability and high reliability, vibration wire strain sensors were extensive applied in many momentous projects. In the paper, the basic principle and working characteristics of vibration wire strain sensors were introduced. Also, those error reasons from the aspect of working principle, the aspect of structural bending deformation and the aspect of temperature field were analyzed. In the end, amendment technology was given out, providing valuable reference of improving structural strain accuracy.

Abstract: Based on present research, there is a big difference between the estimation of the first frequency of Girder Bridge obtained by the design code of bridges, issued by department of transportation of China in 2004, and the theoretical value in some cases. To overcome above issue, theoretical analysis combined with numerical simulation was applied to estimate the fundamental frequency of Girder Bridge with uniform cross-section. The effect of the ratio between side span and central span on the estimating fundamental frequency was discussed in detail. Finally, an improved method was proposed to estimate the first frequency of Girder Bridge, and the effectiveness of the proposed method was verified.

Abstract: Self-anchored suspension bridge is widely used in Chinese City bridge engineering for the past few years. Because the anchorage system of main cable has been changed from anchorage blocks to the ends of the girder, its’ dynamic mechanics behavior is greatly distinguished with the traditional earth anchored suspension bridge. This paper studies the dynamic characteristics and seismic response of one large-span self-anchored suspension bridge which is located in China/Shenyang city. Using a spatial dynamic analysis finite element mode, the dynamic characteristics are calculated out. An artificial seismic wave is adopted as the ground motion input which is fitted with acceleration response spectrum according to the Chinese bridge anti-seismic design code. Time-integration method is used to get the seismic time-history response. Geometry nonlinear effect is considered during the time-history analysis. At last, the dynamic characteristics and the behavior of earthquake response of this type bridge structure are discussed clearly. The research results can be used as the reference of seismic response analysis and anti-seismic design for the same type of bridge.

Abstract: Due to the repeated action of vehicular loads, fatigue failure of suspenders of half-through arch bridge is main failure type. Usually the stress history of suspender is relevant with the vehicle load, dynamic property of structure and so on. In this paper, the traffic load spectrum investigation of Ha-Tong road is constructed through a 24-hour traffic flow investigation; And the space FEM established to get the stress response；Assume the fatigue performance of suspender as stochastic variable, the stress history of suspender is a stochastic process which changes with time, fatigue reliability analysis model is suggested based on accumulated damage model；Taking YIlan bridge as an example, the study on the effect of suspenders’ length and deck type are carried out. The research method and results can be referenced while designing or evaluating the same bridge type.

Abstract: Fiber reinforced polymer (FRP) bars have been widely used in civil engineering used as a substitute for steel reinforcement because it has many advantage such as high strength, light weight and no corrosion. Moreover, the productive technology becomes more and more mature and industrialized so that FRP has become one economic and competitive structure material. Based on the recent researches, this paper mainly introduces progress in the studies on concrete structures reinforced with FRP bars. These contents in this paper include the bond performance of FRP bars in concrete, shear resistance, flexural behavior and ductility of concrete structure reinforced with FRP bars in the past few years in the world.

Abstract: As one of the most important components of CFST arch bridges, the cross beams should affect the bridges’ dynamic performance and response magnificently by means of affecting these three factors mentioned above. Based on the Maocaojie Bridge, its FEM models of half-through CFST arch bridges with different settings of cross beams are built. The different seismic responses of six operating conditions are calculated with three dimensional earthquake waves input. The internal force and displacement envelope diagrams of arch ribs are extracted and analyzed in situations of in-plane moment, out-plane moment, vertical displacement and transverse displacement. It can conclude that the joint section between arch rib and bridge deck should be designed carefully because of its large displacement and internal force, and the cross beams should be optimized to safety the arch bridge dynamic response considering lateral rigidity. The conclusions may be useful to the seismic design and strengthening treatment of CFST arch bridges. To strengthen the joint section between arch rib and bridge deck or optimize the setting of cross beams will increase the ductility of half-through CFST arch bridge and decrease the damages caused by large earthquake.

Abstract: Fatigue is the decay process of the structure stress performance under the action of repeated load. The fatigue essence is the material fatigue damage accumulation process along with the increase in the number of fatigue loading. Because of the structural fatigue damage caused by the great dangers, the fatigue damage problem has been studied by many researchers at home and abroad. In this paper, it systematically reviews the research status of fatigue damage of concrete bridges on the basis of previous studies and the problems for further research are discussed. From the bridge component materials perspective, the paper analyses the status and the development direction of the dynamic constitutive models. At the same time, the paper summarizes the fatigue cumulative damage theory and analyses the advantages and disadvantages of the various theories. The main contents of this paper include: the research history and status of fatigue damage of concrete bridges, the damage variable selection, the fatigue cumulative damage theory, the problems for further research on the fatigue damage of concrete bridge.

Abstract: As the residue level of viscosity reducing in after mixing WMA would dynamic change with paving time and temperature, which should influenced on their compaction performance accordingly. The paper employed a improved variable-temperature control SGC compaction experiment to evaluate the compaction performance of four kinds of typical Warm-Mix Asphalt. In the paper, the compactibility at different temperature and the optimum compaction temperature were two way to represent different aspects of compaction performance. By experiment, the authors believed that the construction energy index is more suitable to express the compactibility than the slope of logarithmic fitting curve. And the authors proposed a equidensity –temperature method which based on analogous principle to determine the optimum compaction temperature. According to the experiment results, there are significant difference in the compactibility development trends and the optimum compaction temperature of different Warm-Mix Asphalt. The overall evaluation information of Warm-Mix Asphalt compaction performance could be get by the combination used of the compactibility development trends and the optimum compaction temperature which based on the improved variable-temperature gyratory compaction.

Abstract: Abstract: This paper investigates the laboratory properties of tire crumb rubber modified (CRM) bitumen mixture. Two types of mixtures containing two binders (pen90 bitumen; CRM bitumen) were used to produce Marshall Sample and determine optimum content. Mechanical performances of bituminous mixtures were evaluated by Chinese wheel rutting test (WRT), 3point beam bending test (3P-BBT) at low temperature, indirect tensile Strength test (ITST) at freezing-thawing cycles. Superpave gyratory compactor (SGC) specimens also were prepared for modulus test. Resilient modulus (E) data were obtained by unconfined uni-axial compression test according to the specification of China. Dynamic modulus (E★) data were obtained by Simple Performance Test (SPT). Two temperatures were used at dynamic modulus test. The results indicate that CRM bituminous mixture performs better than referenced bituminous mixture on viscoelastic behavior, rutting resistance, cracking resistance and moisture stability.