Displacement Time History Curves Research Articles

Simplified Analytical Model and Shaking Table Test Validation for Seismic Analysis of Mid-Rise Cold-Formed Steel Composite Shear Wall Building

To develop the cold-formed steel (CFS) building from low-rise to mid-rise, this paper proposes a new type of CFS composite shear wall building system. The continuous placed CFS concrete-filled tube (CFRST) column is used as the end stud, and the CFS-ALC wall casing concrete composite floor is used as the floor system. In order to predict the seismic behavior of this new structural system, a simplified analytical model is proposed in this paper, which includes the following. (1) A build-up section with “new material” is used to model the CFS tube and infilled concrete of CFRST columns; the section parameters are determined by the equivalent stiffness principle, and the “new material” is modeled by an elastic-perfect plastic model. (2) Two crossed nonlinear springs with hysteretic parameters are used to model a composite CFS shear wall; the Pinching04 material is used to input the hysteretic parameters for these springs, and two crossed rigid trusses are used to model the CFS beams. (3) A linear spring is used to model the uplift behavior of a hold-down connection, and the contribution of these connections for CFRST columns are considered and individually modeled. (4) The rigid diaphragm is used to model the composite floor system, and it is demonstrated by example analyses. Finally, a shaking table test is conducted on a five-story 1:2-scaled CFS composite shear wall building to valid the simplified model. The results are as follows. The errors on peak drift of the first story, the energy dissipation of the first story, the peak drift of the roof story, and the energy dissipation of the whole structure’s displacement time–history curves between the test and simplified models are about 10%, and the largest one of these errors is 20.8%. Both the time–history drift curves and cumulative energy curves obtained from the simplified model accurately track the deformation and energy dissipation processes of the test model. Such comparisons demonstrate the accuracy and applicability of the simplified model, and the proposed simplified model would provide the basis for the theoretical analysis and seismic design of CFS composite shear wall systems.

Experimental Study on the Impact Properties of Concrete Bridge Pier Reinforced with Stainless Steel Rebar

Abstract In this study, in order to examine the impact properties of a stainless steel reinforced concrete bridge pier under the conditions of horizontal impact load effects, a multifunction ultrahigh heavy drop hammer impact test system was utilized. The stainless steel reinforced concrete bridge piers had different impact energies, and the impact force time-history, displacement time-history, and strain time-history curves, as well as the crack developing state, were obtained during the testing. The test results showed that the peak values of the impact force, strain, and displacement increased with the increase of the impact energy under the impact load, and the fluctuation frequency also increased. The crack development was mainly concentrated in the lower frontal section of the bridge pier, as well as the middle and lower sections of the back of the bridge pier.

Experimental and numerical studies on seismic performance of traditional style steel-concrete composite frame

In order to study the seismic performance of a Chinese traditional style steel-concrete composite frame, a half-scale prototype was designed for a region with intensity seven in the Chinese seismic design code. In the experiment, the El Centro, Taft, Lanzhou and Wenchuan ground motions with different peak accelerations (0.035 g, 0.1 g, 0.22 g, 0.4 g) were used to simulate earthquakes of different characteristics and intensities. The displacement response, restoring force and acceleration response of the measured structure were analyzed, and the hysteresis characteristics, failure mechanism, deformability and energy dissipation capacity of the model were quantified. The results show that the damage caused is concentrated in the beams and at the transition zone between the upper and lower column as evidenced by noticeable pinching of the hysteresis curves. The ultimate story drift reached is about 1/157–1/153 (0.65%), satisfying the elastic-plastic limits in the code. At a peak acceleration of 0.4 g, the stiffness of the specimen is 66% lower than that at a peak acceleration of 0.035 g. The most obvious structural response is under the excitation of El Centro wave, while the smallest is under the action of Wenchuan ground motion. The finite element software SAP2000 was used to analyze the failure of the specimen, the displacement time history curve and sequence of the plastic hinges. The calculated values of the finite element are in reasonable agreement with the experimental values, which can supply some reference to the practical engineering application.

Numerical analysis of elastomer buffer embedded in the suspension of automobile for vibration damping improvement

Elastomers, due to their excellent damping and energy absorption characteristics and low cost are used extensively in automobile industry to isolate the structures from vibration and shock loads. In this study, it was aimed to analyze the damping performance of an elastomer buffer embedded in the suspension of an automobile. To reach to this aim, vibration simulation of an automobile suspension model was conducted by using a nonlinear explicit finite element code, Abaqus. In order to simulate the damping behavior of elastomer buffer, the hyperelastic and linear viscoelastic material models were used together. The numerical model was validated with results of exact solution method in terms of transmissibility ratio and phase shift in a wide range of input excitation frequencies. Good agreement was observed between the exact solution and finite element results, which indicate that finite element model is sufficiently accurate. To examine the damping performance of the buffer, the displacement time history curves were extracted for suspension with and without buffer under the sinusoidal base excitation. The vibrating motions of suspension for both conditions were compared. The comparison results proved that the elastomer buffer was effective in improvement of damping performance of suspension. It reduced the amplitude of vibration and oscillation time of sprung mass remarkable in excitation frequencies around and over the natural frequency of the system.

DEM Algorithm for Progressive Collapse Simulation of Single-Layer Reticulated Domes under Multi-Support Excitation

ABSTRACTIn this paper, the Member Discrete Element Method (MDEM) is modified and perfected for three aspects: the algorithm itself, loading and computational efficiency, and to accurately and quantitatively simulate the progressive collapse for large-span spatial steel structures. In addition, the corresponding computational programs are compiled. First, from the perspective of the method, a meshing principle for discrete element models is determined, a treatment for material nonlinearity and strain rate effect is proposed, and a damping model is established. Next, the Displacement Method is introduced to determine the multi-support excitation for the MDEM, and then motion equations of particles under multi-support excitation are derived. On this basis, the specific process of gravitational field loading is presented. Furthermore, parallel implementation strategies for the MDEM based on OpenMP are constructed. Finally, the collapse simulation of a 1/3.5-scaled single-layer reticulated dome shaking table test model under multi-support excitation is carried out. The comparison demonstrates that the ultimate load and failure mode as well as the complete collapse time of the numerical results are consistent with the experimentally measured responses, and the configuration variations from member buckling and local depression until collapse failure are fully captured. Moreover, the displacement time-history curves obtained using MDEM are almost identical to the experimental measurements, and there is a nuance only in the amplitude. It is verified that MDEM is capable of precisely addressing the collapse failure for large-span spatial steel structures. Additionally, the failure mechanism for structures of this type is naturally revealed.

The numerical simulation on dynamic response of Tibetan traditional stone-wood structure under earthquake action

Based on the existing test data obtained from preliminary study, the numerical modeling work for the characteristics of Tibetan traditional Stone-wood structure was performed in this paper. The mode of vibration and frequency were researched by modal analysis method. Meanwhile, the time history curves of displacement at different parts of structure and peak displacements were obtained after simulating the dynamic response of structure under frequent earthquakes. And the weakest parts and damage characteristics under the frequent earthquakes have been summarized. Studies showed that the shapes of displacement curves at different parts of structure were so similar that the displacement of all components reached to the peak at the same time. Finally the weakest parts of Tibetan Stone-wood structure were parapet walls with the largest peak displacement under earthquake and walls near to structural opening were easier to be destroyed than others.

Progressive Collapse Analysis of Concrete-filled Steel Tubular Column to Steel Beam Connections Using Multi-scale Model

The multi-scale model which combined the fiber beam element with the fine element was used to investigate the progressive collapse performance of steel beam to concrete-filled steel tubular (CFST) column connections. By using the nonlinear static analysis method and taking into account the influence of the adjacent framework of joints, the resistance of progressive collapse, the failure modes and the stress distribution revealed the resistance mechanism of these joints during the process of progressive collapse. And the vertical displacement time history curves of joints which displayed the progressive collapse resistance demands of these joints were obtained by using the nonlinear dynamic analysis method. The relationship between resistance capacity and resistance demand of these joints were obtained by analyzing the nonlinear static analysis results and the nonlinear dynamic analysis results. These analysis results showed that the frame structure with these joints which enabled to form the resistance mechanism and new alternate path of unbalanced loads can prevent the occurrence of progressive collapse after the failure of column connected to joints. And the adjacent framework can improve the ability of anti-progressive collapse of these joints.

Design of Vibration Excitation Test Rig with Redundant Degree of Freedom

In order to provide controlled indoor experiment condition for the anti-vibration performance test of vehicle suspension, the multi-link vibration excitation test rig with redundant degree of freedom, which can simulate the different roughness roads and can produce stable, ergodic, random vibration excitation, was designed in the paper. First, according to the different redundant degrees of freedom, the four and three degrees of freedom vibration excitation test rig structural schemes were designed respectively, and the solid model and motion simulation of vibration excitation test rig were performed based on virtual technology, then the time history curves of displacement, velocity and acceleration at work bench were obtained. Second, vibration properties and characteristics of the two schemes were ascertained by using self-power spectral density, symbol time series histogram and Shannon entropy, thereby three degrees of freedom scheme was considered better on the basis of random vibration level and impact force of mechanism. Finally, acceleration root mean square of work bench was set as evaluation index of vibration excitation test rig’s vibration excitation energy, and support distance, driven-crank rotation speed and spring stiffness under work bench were selected as influencing factors, then three factors and three levels of orthogonal design was conducted to determine three grades of vibration excitation test rig.

Experiment Research on the Shock Resistance of Magnetite Concrete

Through magnetite concrete beam under the action of gravity drop hammer impact dynamic bending test, reasonable testing program was designed to realize the whole process of dynamic test data acquisition, beam load and impulse, time history curves of displacement and force dynamic force - displacement curve and dynamic strain of fracture zone curve. By observing the destruction of the different strain rate，the constitutive relation of dynamic strength changing with the loading rate and input energy was studied. At the same time, the strain rate，the fracture process of different rate of damage and the destruction form need to be found.

LABORATORY TESTS ON WATER-SATURATED RHEOLOGICAL PROPERTY OF CARBONACEOUS ARGILLACEOUS LIMESTONE

The water-saturated direct shear rock rheological test is carried out on the carbonaceous argillaceous limestone at the slip zone of Jiweishan landslide, Wulong, Chongqing. A rock direct shear rheometer is used. The rheological test results give the shear stress-shear displacement time-history curves of the slip zone and the long-term strength parameters of the rock. The results show that: the long-term strength in the water-saturated conditions significantly decreases, comparing to the rheological strength in the natural conditions and the instantaneous shear strength parameters. The internal frictional coefficient of the carbonaceous argillaceous limestone in the water-saturated conditions is lower than that of natural rheology 13.87%, and lower than that of the instantaneous shear 40.91%. The cohesion of the carbonaceous argillaceous limestone in the water-saturated conditions is lower than that of natural rheology 13.81%, and lower than that of the instantaneous shear 36.67%. Because of the crack damage propagation, the long-term shear strength in the water-saturated conditions decreases, comparing to that in the natural conditions, but does not decrease significantly, comparing to the long-term shear strength of the direct shear rheological test and the instantaneous shear strength. These findings can provide the important experimental and theoretical basis for in-depth understanding and analysis of the rheological mechanical properties of the slip zone soft rock in Jiweishan landslide.

The Mechanical Properties of Barite Concrete Subjected to Impact Loading

In order to understand the mechanical properties of barite concrete subjected to impact loading, use the drop-weight experiment according to the stress, strain and displacement to find out. The experiment is designed in two ways, using different qualities of drop hammers falls in the same height or using the same quality of drop hammers falls in different height. And know the failure process of barite concrete when the area of strain rate is 1.4s-1~4s-1, and making reference to the stress time-history curves, the strain time-history curves and the displacement time history curves, comes to the conclusion that in the case of other conditions remain unchanged the peak load, the loading rate and so on will increase if make the drop hammer heavier or higher.

Seismic Experimental Study on Masonry Structure Strengthened by Ring-Beam and Constructional Column

A full scale masonry model of two-floor and single bay was built in this paper and was strengthened by ring-beam and constructional column. And then pseudo-dynamic testing was conducted to study the time-history curves of displacement, velocity, acceleration response and restoring force in 7 degree rarely earthquake. Results show that the earthquake performance is steady and there are no visible cracks on the model after the testing. Windows and doors perform well because of the constraint of ring-beam and column, whereas failures often occurred when the structures were not strengthened. Seismic performance is largely improved by ring-beam and constructional column and the structure can resist 7 degree rarely earthquake.

Study on the Impact Properties of a New Debris Flow Dam Based on Steel-Concrete Composite Structure

The impact force is one of the most weak link of the dynamics studies of debris flow for many years. To make the structure or components are better able to suffer the impact load such as debris flow, explosions, a new debris flow dam is designed by introducing this new type model with spring. It is simulated under boulder impact by using finite element software LS-DYNA.The stress distribution, impact and displacement time history curve under typical conditions are obtained. The results show that the resist impact effect of new debris flow dam is very obvious.

Numerical Analysis on Anti-Seismic Dynamic Response of Rectangular Caisson Foundation

Based on the software FLAC3D, we set up the dynamic calculation model. By applying the horizontal (x direction) seismic waves at the bottom of the model, we simulate the earthquake action to the caisson foundation and the soil body around it and obtain the time-history curves of the acceleration, the velocity and the displacement of the key points in the model in x direction. We also obtain the rotation angle time-history curve and the relative displacement time-history curve of two key points at the bottom of the caisson foundation. Through the analysis on these curves, we know the maximum values of the acceleration, the velocity and the displacement of the top portion of the caisson foundation are 393.6 cm/s2, 75.9 cm/s, 28.5 cm, and the maximum rotation angle of the caisson foundation is 0.08°. We sure the bond of the caisson foundation bottom and the below soil layer is firm and the relative displacement is only 1.3 mm. Looked from the overall,the anti-seismic property of the caisson foundation is good. The above results provide a reliable basis for the future research on the dynamic response of caisson foundation.

Numerical Analysis on Dynamic Responses of the Reinforced Concrete Piers under Impact Loads of Mass Objects

In this paper, based on the drawing of an actual project, the dynamic responses of reinforced concrete piers under impact loads of mass objects were researched by using the finite element analysis software ANSYS/LS-DYNA. A common node separate model was adapted to the dynamic responses. The results indicated that vibration frequency at the top of pier column along the transverse direction was more than that in the impacted position under the action of impact. And after analyzing displacement time history curve and maximum displacement at different parts of pier column, the position with maximum displacement in different working conditions was summarized.

Dynamic Test of Bird Strike on a Flat Plate Made from LY-12 Aluminium

Tests of bird strike have been carried out on plate made from LY-12 Aluminium. The test was down with the projectile impacting the target perpendicularly at velocity of 40m/s, 80m/s, 120m/s respectively. The displacement-time history curves and strain-time history curves of on LY-12 Aluminium plate were measured. The good agreement of the results between two specimens in one group indicated that the results tested in the presnet paper are reliable. The dynamic response of the plate and damage modes of the bird influenced by striking velocity were analyzed. The peak value of the displacement linear enlarged with the increasing of the striking velocity. The test results in the present paper provided valuable data for aircraft design impacted by bird, and also provided abundant test datas for the numerical simulation model applied in bird striking.

Dynamic Performance Analysis of Steel Truss Bridge

Steel truss bridge is an important part of transportation hub and lifeline engineering, it recently has attracted more attention on dynamic performance of steel truss bridge. In this paper, the ANSYS software is used to perform the modal analysis of steel truss bridge, and we find that the main bridge are more sensitive to the vertical earthquake (i.e., Y direction). In the earthquake response spectrum analysis on Y direction, we find that the maximum deformation is at mid-span of steel truss bridge. In the transient analysis of seismic waves, under the action of horizontal and vertical earthquake accelerations, the structure displacement dynamic diagram and time-history displacement curve are obtained and some conclusions are drawn.

Influence of Different Earthquake Excitations on Dynamic Stability of Single-Story Steel Frame

Dynamic stability analysis of twelve single-story steel frame structures is analyzed based upon the finite element method. The influence of different earthquake excitations on dynamic stability of single-story frame is studied. Time history curves of displacement, hysteretic curves of restoring force, phase plane trajectory curves have been obtained. The results indicate that the ultimate displacements of frames when structures collapse are almost identical and ultimate displacements are independent of earthquake excitations.

Finite Element Analysis of Bullet Penetration Circular Sandwich Plate

A nonlinear dynamic finite element method based on ANSYS/LS-DYNA is used to simulate the physical process of a bullet penetrating circular sandwich plate at a speed of about 400 m/s. In the simulation, Lagrange algorithm, Johnson-Cook and Crushable-foam constitutive model are choosed. Energy time history curve, impact force time history curve, Von-Mises stress nephogram and displacement nephogram are obtained. At the same time, stress time history curve of the maximum stress element and displacement time history curve of the maximum displacement node are obtained. Compared with the non-sandwich plate, it is found that the use of sandwich plate can reduce the total mass, inner plate stress and displacement, and can protect inner plate well.

Numerical Simulation of Polyurethane Strengthened Perforated Masonry Walls under Blast Loading

In order to investigate the explosion resistance performance of perforated masonry walls strengthened with polyurethane, nine numerical models with different layer number and different strip width of polyurethane are established in this paper. Deformation drawings and time history curves of displacement of the numerical models are comparatively analyzed. It is found that there are two failure modes, global failure and local failure, of strengthened masonry walls and the differences of failure patterns are significant between various types of strengthening method.