Papers by Keyword: Dynamic Response Analysis

Abstract: To mitigate the effect of earthquake on the structure, the base isolation technique is the best alternative as a seismic protection system. In this research, a two-degree-of-freedom (2DOF) equivalent model is modelled based on a real eight-level reinforced concrete structure damaged by the Boumerdes earthquake in 2003 is presented. The basic isolation systems considered are four models namely: the first system is a high damping isolator (HDBR), the second system is the friction pendulum isolator (FPS). The third model of the base isolation system is a non-linear model with two horizontal and rotational stiffness springs (SHRS), and finally the last model presents a bilinear spring (SB). The isolators are designed according to the UBC-97 code. Earthquake recordings from Dar-El-Beida of the 2003 Boumerdes earthquake were used as seismic load. A dynamic analysis of the comparative temporal responses of the structure was performed by comparing its dynamic behaviour with that of the fixed base structure. The results obtained reveal a reduction in base shear, stage drift and stage acceleration and an increase in displacement and time period for the structure isolated at the base. The results are presented in tables and graphs.

Abstract: After analyzing the propagation of stress wave at different angles of inclination, strength parameters and the group number of structural plane. The results of research are summarized as follows: Due to the change of propagation direction in structural planes with different angles of inclination, the original propagation rule of stress wave changes too, the peak velocity of the monitory point gets relatively flat as the strength parameters of structural plane turn greater. Stress wave repeatedly refracts and reflects in many groups of structural plane, then the appropriate dynamic characteristics of the wave no longer maintains as the number of group increases or decreases. By analyzing and verifying the slope instance, the test result provides a reference for studying dynamic response rules.

Abstract: It will stir up the vibration of asphalt deck surfacing when the Vehicles pass through the steel bridge deck. The research of the moving vehicles vibration characteristics of the deck surfacing has been one enthusiastic concern. By the time history analysis method of finite element, the paper studied the dynamic response of the deck surfacing in different speeds of vehicles, and then analyzed the effect of the deck surfacing by different speeds.

Abstract: This paper uses both numerical simulation method and experimental research method to study on welding residual stress of high-strength steel of the cone-cylinder hull. Welding is often accompanied by a larger welding residual stress, which directly affects the safety and service life of the hull structure. In order to obtain the distribution of the welding residual stress, the welding procedure was developed by its parameter language by using FE analysis software in this paper. Then the welding residual stress of hot spot region was measured through X-ray nondestructive testing method, and compared it with simulation results. Finally, considering the residual stress as the initial stress, this paper analyzed dynamic response process of the welding structure under combined actions of the welding residual stress and multiaxial loads, which could more accurately determine the stress of welding structure and the location of fatigue risk point. According to the amplitude of damage parameters and strain time-history curve, we can estimate the fatigue life of structure by selecting the corresponding damage models.

Abstract: With the rapid development of high-speed railway, dynamic interaction between vehicles and track is correspondingly strengthened. Therefore, dynamic responses analysis of the high-speed vehicles and track become more and more important to the train operation safety, riding comfort as well as the maintenance of railway infrastructure. In this paper, vehicle and track vibration equations are separately established based on the vehicle track vertical coupling model. Taking the CRH vehicle running on the existing line as an example, the random vibration responses of the vehicle and track under different running speed are analyzed in time domain through numerical integral method and MATLAB program. According to the results, the velocity of train has more influence on the vibration property of rail and wheelsets than bogie and carbody.

Abstract: With the economy developing rapidly, China has entered the era of high-speed railway, but at the same time, the negative impact of high-speed railway is increasing obviously. The paper analyzes the induced environmental vibration problems due to the high-speed railway, the specific response in the power of the shield tunnel under the train loads, the tunnel structure and the surrounding strata, When the local layer is saturated sand, by calculating the pore water pressure and the layer stress, determining whether it can cause sand liquefaction phenomenon or not, judging the damage extent of tunnel structure, especially it may influences the normal operation of the train. The vertical displacement of the tunnel structure due to the dynamic train load may have impact on the normal operation of the train, where some preventive measures should be taken, such as concrete grouting reinforcement method. In this paper the non-reinforcement case is compared to the reinforcing ones, and different reinforcement ring thickness is studied in order to determine a reasonable thickness of the reinforcement. The main contents include the following work: （1）Response analysis by using the FLAC3D software to simulate the shield tunnel under the dynamic train loads which are the main cause of the displacement of the segment and surrounding strata. The simulation study mainly includes analysis of the changes of pore water pressure and stress. （2） Since train load can produce the vertical displacement, prevention and controlling measures should be taken, which mainly use grouting reinforcement.

Abstract: Based on the theory of soil-structure interaction, the underground structure and surrounding soil as a system, and the finite element analysis model is established, and finite element dynamic analysis method is implemented, the three seismic acceleration time history of the different spectrum characteristics is inputted, the seismic effect on the surrounding ground of underground structure is analyzed. The results show that the effect on dynamic response is the limited range and not significant, when seismic design of structures on the surrounding sites is implemented, additional dynamic response on surrounding sites does not need to consider.

Abstract: In consideration of the deficient study on dynamic response of reinforced concrete silos, especially group silos at home and abroad, taking the silos of one grain storage for instance, the dynamic response analysis of a single column-supported silo and that of group silos are carried out and contrasted through finite element method. Then the analysis results are contrasted with corresponding standards as well as academic studies.

Abstract: A collision between a 2600 DWT oil tanker and the substructure of one railway continuous beam bridge is simulated using ANSYS/LS-DYNA. In the simulation, the dynamic interaction between the soil and piles is considered through contact coupling algorithm and nodes sharing algorithm. The time history of ship collision force, penetration and velocity of the ship for the two different algorithms are presented, and relations of them are given. In addition, energy dissipation in every parts, deformation response and stress distribution of the substructure are analyzed in detail. The results indicate that rules of ship-bridge collision given by the two algorithms are in good agreement. Finally, reliability of the simulation in this paper is demonstrated through the comparison with specifications.

Abstract: Current guidelines such as TM5 and ASCE use a trial and error procedure to design RC slabs against blast loads. Although the trial and error procedure is easy to implement, it may not result in a optimal to resist blast loads. In this study, SDOF system recommended by TM5 and ASCE was adopted to simplify RC slabs; the bilinear model was selected to simulate the resistance-deflection curve for dynamic response analysis. After comparing the areas under the resistance-deflection curves of RC slabs with different reinforcement ratios, the reinforcement ratio responding to the biggest area can be defined as the optimal reinforcement ratio. These derived relationships are useful to facilitate a design with maximum capacities to resist blast loads.