Yan Jiang Chen

Seismic Testing of a Long-Span Concrete Filled Steel Tubular Arch Bridge

Long-span bridges are always a multi-support structural system, and seismic ground motion can vary significantly over distances comparable to the length of such kind of bridges, so it’s difficult to carry out shaking table tests because of the restriction of the dimension and amount of shaking tables. This paper discusses the multiple sub-table cordwood system is used to conduct a study on the seismic testing of a three-span irregular Concrete filled steel tubular (CFST) arch bridge with the objective of investigating the dynamic performance of the bridge under spatial earthquake motions. The development and testing of the bridge model and selected experimental results are discussed then. The seismic response and response characteristics of acceleration, displacement, internal force, and strain of the structure under earthquake excitations are gained, which can provide test data and basis to evaluate the seismic performance of this CFST arch bridge or other similar structural system design.

Nonlinear Seismic Response Analysis of Half through CFST Arch Bridge under 3-D Earthquake Waves

A finite-element model for CFST members using a 3D composite beam fiber element is presented which accounts for the nonlinear constitutive models of steel and concrete separately. The model is proved to be valid by comparing the computational results of some test specimens with their experimental data. Using this model, a CFST arch bridge’s seismic response was calculated. The result indicated that the magnitude of displacements and moments at arch crown increases up to 10 percent caused by CFST hysteretic behavior which should be seriously considered during seismic design. Some measures and suggestions bring forward to guide the design and construction of this type of bridge.

Effect of Laminar Flow to Velocity Exponent of Viscous Damper

The relationship between the energy dissipation and the damping force is studied through experimental and analytical research of the effect of laminar flow of viscous damper, and a linear viscous damper model and the calculation formulas are obtained.The results show that the linear flow model is the key factor to get a linear relationship between speeds and damping force.

Seismic Analysis of a Low Tower Cable-Stayed Bridge and Application of Lead Shear Damper

A low tower cable-stayed bridge with a span of 30m+60m+120m+60m+30m had been built before Guidelines for Seismic Design of Highway Bridge was promulgated. Because of its impor¬tance and specificity, it is necessary to do research on seismic performance of this bridge. According to the numerical analysis, it is found that the structural response exceeds the allowance and the bridge might be destroyed if earthquake happened. Here, energy dissipated technology is chosen to cope with this problem. But traditional lead shear damper hasn’t the capabilities of large deformation for some reason and can not be applied to bridge engineering in general case. In this article, a new type of lead shear damper with capabilities of large deformation is used to achieve energy dissipation. Through comparing, it is found that the damping effect of this new damper is as good as that of viscous damper. And the damper has no problem with leakage and metamorphism. What’s more, it is much cheaper than vis¬cous damper. So, lead shear damper has a good prospect in bridge damping.

Temperature Analysis in Durability Test of the Viscous Damper

The cylinder is prone to be damaged due to temperature increasing in vibration control and durability testing process of viscous damper. In order to avoid the overheating generated by long working hours, which resulting in a viscous liquid water evaporation and leading to a abrupt increase in internal pressure inside the cylinder, the CFD software Fluent was used to simulate the durability test process of the oil film, where the heat was easy to generate and suggestion for improving the viscous damper was proposed.

Experimental Research of Uniaxial Compression Bearing Capacity on Large Diameter CFST Columns

This paper focused on the uniaxial ultimate-bearing-capacity of large size concrete filled steel tubular (CFST) columns. Two aspects were investigated experimentally. To verify the feasibility of similarity principles for large size components, a series of uniaxial compressive experiments were conducted using different scaled specimens, the prototype of which is a CFST arch rib in an authentic arch bridge. Meanwhile, two specimens with same scale were tested axially and eccentrically to investigate the difference of bearing capacity resulted from the pierced-column. The experimental results show that the size effect on the bearing capacity of the rib is so insignificant that the scaled specimen can be used to obtain the maximum capacity of the full-scale component. The inserted steel tubes in the middle of the column cause the reduction of its capacity and the reduction factor from axial loading is bigger than that from bias load. Moreover, the eccentricity reduces the effect of piercing on the capacity of CFST column.

A Method for Damage Detection Based on Correlation Characteristic of Acceleration Response

A damage detection method using BP neural network based on a novel damage index, the correlation characteristic of the acceleration response, is proposed, and is evaluated through the FEM simulation and experiment verification. On the basis of achievements in existence, the feasibility of using the correlation characteristic as damage index is validated theoretically. The damage detection for a simple-supported beam using the proposed method was FEM simulated. The results showed that the trained BP neural network can correctly detect the location and extent of damages in both single damage case and multi-damage case. A model test of a reinforced concrete simple-supported beam was performed to verify the validity and efficiency of the damage detection method. From the results of the model test, it is shown that the trained BP neural network can correctly locate the damage mostly detect the extent of damage. A conclusion is given that the novel damage detection method using the correlation characteristic of the acceleration response as damage index is feasible and efficient.

Study on Dynamic Characteristics and Parameter Sensitivity of Three Spans Prestressed Continuous Beam

Established the three spans prestressed continuous beam dynamic equation, obtained analytical expression of frequency equation. To solve the frequency equation for natural frequency, and compared with the finite element numerical analysis results, the frequency both with analytical expression and with finite element are in good agreement. The formula can be obtained accurately the dynamic parameters of three spans prestressed continuous beam such as frequency. At the same time, the paper also studied the natural frequency sensitivity analysis of three spans prestressed continuous beam, and focuses on the impact on the frequency with effective prestress and prestressed eccentricity.

Nonlinear Analysis on the Anchor Board of the Cable-Girder Anchorage Zone of a Cable-Stayed Bridge

The cable-girder anchorage zone of cable-stayed bridge is vital to the safety of the entire structure. Aiming at uniformly conveying the vehicle and populaiton load as well as the load of the main girder to the cables, this zone shows unique characters with concentrated and massive loads, complex structures, comprehensive load paths and non-uniformly stress distributions. This paper established the 3D finite element modal for the Ronggui Cable-Stayed Bridge. A nonlinear analysis on its anchorage zone has been conducted to provide reasonable references for future design and optimization.

Seismic Response of a Viaduct under near-Fault Earthquakes

Abundant long-periodic components endue near-fault earthquakes with large velocity pulses while the viaducts owe long periodic fundamental period. To explore the seismic response patterns of viaducts under near-fault earthquakes, the paper analyzed the time history response of a viaduct under near-fault seismograms including TCU 1063, TCU 065, El centro and Artificial wave via FEM software Civil. The analysis shows a significant boost in near-fault seismic response as the value of PGV/PGA increased accordingly, indicates that the near-fault pulse affects strongly on the structural dynamic response of the viaducts.