Ai Rong Liu

Deformation and Energy-Based Seismic Damage Evaluation of Steel Reinforced Concrete and Reinforced Concrete Piers

The method of MMCP (modified modal cyclic pushover) which can reflect the dual criterion of deformation and energy was used to make an assessment on seismic performances of the steel reinforced concrete piers and reinforced concrete bridge piers. Then the calculated results were analyzed comparing with the results of dynamic time historical analysis and quasi static test. To some extent, the MMCP analysis may simulate the seismic action. In addition, the MMCP method can also be associated with the design response spectrum, making the evaluation results to be reliable and safe. The results indicate that MMCP applicability analysis also exists in the steel reinforced concrete structure, and the seismic capacity of steel reinforced concrete bridge piers is better than reinforced concrete bridge piers.

Mechanics Study on the Leaning-Type Arch Bridge during the Construction Process Based on Building Materials

With the constructing project of Shengli Bridge as the background, this paper presents the measured stress and deformation data of main arch rib during the process of full framing scheme. The measured data are compared with the computation results.And the mechanical behaviors of the arch bridge were studied to reveal the changing tendency of stress and displacement of the main arch construction completed to completion stage. The analysis results show that the stress and the displacement of the key structures are in a reasonable range and meet the design requirements during the process of the construction process.

Analytical Solution of Sidewise Buckling of Two-Hinged Circular Arch under Concentrated Force

By the setting torsional and lateral displacement function of sidewise buckling of two-hinged circular arch under concentrated force, the single-arch structures bending, torsional deformation and external force potential can be constructed. An analytical solution for the lateral critical buckling load of two-hinged arch is first deduced by using the energy method; the results are also compared and analyzed by the finite element method. The results show that the analytical solution of single arch’s lateral critical buckling load is in good agreement with the finite element numerical solution, and the validity of the formula is proven.

The Effect of Inclined Arch Rib on the Dynamic Stability of Leaning-Type Arch Bridge under Earthquake

Incorporating the Lyapunov theory of motion stability, the elastic dynamic stability program of a leaning-type arch bridge with 120m span is worked out via the modified freeing time method. The dynamic eigenvalue-time history curve and dynamic buckling modes are presented, and the effect of inclined arch rib on the dynamic stability of leaning-type arch bridge is analyzed and compared under the seismic exercitation in the longitudinal, transverse and vertical directions of the bridge. The results show that all of the dynamic buckling modes are out-plane instabilities when the effect of inclined arch rib is not considered, while dynamic stability coefficient increases by 6%, 56% and166% respectively when the effect of inclined arch rib is considered.

The Study of Lateral Buckling for Leaning-Type Arch Rib System under Hinged Boundary Condition

This paper takes leaning-type arch ribs system as research subject. And based on the Ritz method, the analytic solution of the lateral buckling critical load of leaning-type arch ribs system under the arch springing hinged boundary condition is derived. Compared with the result obtained from FEM, it is verified that the lateral buckling critical load analytic solution presented in this paper is accurate enough. On that basis, the effect of boundary condition on the lateral bucking critical load of leaning-type arch rib system is analyzed. It is shown that the lateral stability of the leaning-type arch rib system under arch springing clamped boundary condition is much better than the one under hinged boundary condition. And the former’s lateral bucking critical load is 2.13~2.49 times as large as the latter’s. Stable arch inclined angle growing, the leaning-type arch rib system’s lateral bucking critical load increases effectively. But its amplitude under hinged boundary condition increase larger.

Random Seismic Response Analysis of Leaning-Type Arch Bridge

With an example of steel pipe concrete leaning-type arch bridge, space truss system Finite Element Analysis model is constructed using the Ruiz-Penzien random seismic vibration power spectrum model. The impact of inclined arch rib angle and the number of cross brace between main and stable arch ribs on the seismic internal force response under lateral random seismic excitation is also studied in this research. Research finding shows, the in-plane bending moment of main arch rib gradually increases with increasing stable arch rib angle and cross brace, whereas the out-of-plane bending moment and axial force display a decreasing trend. In general, this indicates that increasing stable arch rib angle and number of cross brace improves the lateral aseismatic performance of leaning-type arch bridge.

The Study of Aseismatic Performance of Continuous Rigid-Frame Bridge

The aseismatic performance of long span continuous rigid-frame bridge is an important but difficult research topic. To explore the impact of pier height and reinforcement ratio on long span continuous rigid-frame bridge’s aseismatic performance, Midas/Civil bridge Finite Element program is used to construct the three-dimensional model of a continuous rigid-frame bridge in this research. Fiber element and plastic hinge are used in pier simulation. Through the adjustment of pier height and ratio of reinforcement, the internal force, displacement and plastic rotation of bridge pier’s critical sections are analyzed under the action of seismic loading. Thereby, the impact of pier height and plastic hinge on such bridge’s aseismatic performance is obtained. It is shown that: maximum displacement, bending moment and plastic rotation increase at pier cap with pier height, indicating that pier height has strong impact on seismic response. And with increasing reinforcement ratio, the bending moment and yielding moment at pier cap and base both increase. Therefore, suitable pier height and reinforcement ratio should be selected for better aseismatic performance.

The Seismic Response Analysis of Continuous Rigid-Frame Bridge - Energy Method

A 3D Finite Element model of a continuous rigid-frame bridge is constructed by the Midas/Civil bridge finite element analysis program in this paper, where fiber elements and plastic hinges are used for bridge piers. The lump mass method is used to simplify the infinite-degree-of-freedom continuous rigid-frame bridge into a multi-degree of freedom model. The energy solution of continuous rigid-frame bridge is given, and the time-history analysis of the bridge is applied. In addition, the energy response of continuous rigid-frame bridge with different pier height and reinforcement ratio are given based on the energy method, revealing the impact of pier height and reinforcement ratio on the displacement and energy response of continuous rigid-frame bridge.

A New Type of Hybrid-Passive-Damper

This paper investigated the superelasticity and hysteresis characteristics of TiNi shape memory alloy ( SMA ) wire at room temperature, then the mechanical parameters of which were obtained. Based on the TiNi SMA wire and a purchased viscous damper, a new type of hybrid-passive-damper was designed and developed. Experiments were performed in order to validate the relationship of loading frequency and characteristic parameters such as energy dissipation capacity, equivalent damping ratio and equivalent stiffness. Experimental results show that hybrid-passive-damper designed in this paper has excellent energy dissipation capacity and is suitable for the vibration control of structures with long vibration period.

The Effect of the Varied Temperature and Humidity on Creep Deflection in Service Stage of Bridges

The creep deflections in service stage of bridges are discussed with the effect of the variable temperature and humidity on creep. A coefficient of equivalent duration of loading (CEDL) is proposed, which is an indicator of the effect of the variable temperature and humidity. According to the periodicity of the climate and based on the recorded and collected daily average temperature and humidity in five cities in Pearl River delta from 2002 to 2006, the monthly average CEDL and the yearly average CEDL are thus given to study the effect of the variable temperature and humidity on the creep deflection of a five spans single plane cable-stayed bridge. It is demonstrated that the effect of the variable temperature and humidity is notable in the early phase but inapparent in the later phase of the service stage of the bridge.