Analysis Of Seismic Behavior Research Articles

Experimental study on seismic behavior of exterior composite beam-to-column joints with large size stiffened angles

The top-and-seat angles with double web angles are commonly used in the design of beam-to-column joints in Asian and North American countries. The seismic behavior analysis of these joints with large cross-section size of beam and column (often connected by four or more bolts) is a challenge due to the effects from the relatively larger size of stiffened angles and the composite action from the adjacent concrete slab. This paper presents an experimental investigation on the seismic performance of exterior composite beam-to-column joints with stiffened angles under cyclic loading. Four full-scale composite joints with different configuration (only one specimen contain top angle in concrete slab) were designed and tested. The joint specimens were designed by considering the effects of top angles, longitudinal reinforcement bars and arrangement of bolts. The behavior of the joints was carefully investigated, in terms of the failure modes, slippage, backbone curves, strength degradation, and energy dissipation abilities. It was found that the slippage between top-and-seat angles and beam flange, web angle and beam web led to a notable pinching effect, in addition, the ability of the energy dissipation was significantly reduced. The effect of anchored beams on the behavior of the joints was limited due to premature failure in concrete, the concrete slab that closes to the column flange and upper flange of beam plays an significant role when the joint subjected to the sagging moment. It is demonstrated that the ductility of the joints was significantly improved by the staggered bolts and welded longitudinal reinforcement bars.

Seismic Behavior and Finite Element Analysis of Reinforced Concrete Short Columns Impacted by Oblique Earthquakes

This study evaluates the seismic behavior of reinforced concrete (RC) short columns with a high axial compression ratio under oblique earthquake conditions. The studied parameters include the loading angle, axial compression ratio, the high‐strength stirrups with small spacing, and the carbon‐fiber‐reinforced polymer (CFRP) wrapped column end or outer steel plate mesh at the end of the column. Low‐cycle repeated loading tests were used to analyze the specimens’ seismic performance indices of hysteretic behavior, strength, stiffness, deformation capacity, and energy dissipation capacity. Results suggest that the OpenSees finite element program can sufficiently simulate the nonlinear response of the specimen. Oblique loading led to the increase of damage to the specimens and the deterioration of stiffness of the specimens, which was especially seen with the increase of the axial compression ratio. Accordingly, arranging high‐strength stirrups with small spacing and the column end outer steel plate mesh both transform the failure mode from shear failure to bending shear failure. Additionally, wrapping the CFRP at the end of columns improves their strength but does not improve their deformation capacity. The demonstrated success of these strategies in improving the seismic performance of RC short columns under diagonal loads with high axial compression ratios can inform practical engineering applications.

Seismic Behavior Analysis of Damaged Steel Fiber‐Reinforced High‐Strength Concrete Frame Joints Strengthened by FRP

In this paper, the seismic behavior of fiber‐reinforced polymer (FRP) strengthened and unstrengthened steel fiber‐reinforced high‐strength concrete frame joints under low cyclic loading was tested. Then, the nonlinear finite element program was used to simulate the seismic behavior of FRP strengthened and unstrengthened steel fiber‐reinforced high‐strength concrete frame joints under low cyclic repeated load. The influence of FRP bond direction on the seismic behavior of steel fiber‐reinforced high‐strength concrete frame joints was studied. Through the comparison of the test values and numerical simulation values of the hysteretic curve, skeleton curve, energy dissipation capacity, displacement ductility, bearing capacity degradation, stiffness degradation, and other performance indexes of frame joints, the rule was obtained. The results showed that the 45° bonding direction of carbon fiber cloth is better than the 0° bonding direction, and the digital simulation results are in good agreement with the test results. Therefore, the constitutive model, element, end constraint, and loading method used in the finite element numerical simulation of this paper were reasonable, which can provide reference for the similar research in the future.

Seismic behavior analysis of wind turbine tower affected by hydrodynamic pressure based on a simplified calculation model

Abstract The interaction between water and structure will inevitably lead to the hydrodynamic pressure, which could change the dynamic behavior of the wind turbine tower under earthquake action. Based on the Morison hydrodynamic theory, a simplified calculation method of hydrodynamic pressure was proposed, and the effects of different water depths and hydrodynamic pressure on the seismic behavior of the wind turbine tower is investigated. The main results include: wind turbine tower in deep water is sensitive to water, and the deformation and energy dissipation capacity of the wind turbine tower are decreased affected by the hydrodynamic pressure; the influence of hydrodynamic pressure on the acceleration and displacement is related to the high frequency components of the seismic wave, and the effect of hydrodynamic pressure on the internal force, displacement, and acceleration increases with the increasing of the water depths under different earthquakes. Finally, a shaking table test is carried out, and the experimental results are in good agreement with the calculated results using our proposed method.

Seismic Behavior Analysis of Seismic Isolated Structure by Spectrum-compatible Bi-directional Seismic Accelerograms

Seismic Behavior Analysis of Seismic Isolated Structure by Spectrum-compatible Bi-directional Seismic Accelerograms

Parametric Study of the Modal Behavior of Concrete Gravity Dam by Using Finite Element Method

Calculating the natural frequency of dams is an essential part of its seismic behavior analysis. Therefore, it is important to calculate the natural frequency. This paper aims simulation and analysis the finite element (FE) model of the Koyna concrete gravity as a case study. For the investigation of the suitable mesh size to achievement the grid independence, the element size considered as a variable parameter and calculated its optimized value by using the Response Surface Optimization (RSO) method. In the independent grid, the Error Contour utilized for controlling mesh quality, which indicates fast variations of the energy in the adjacent elements and can recognize parts of the model that has a high error in calculating responses. The modal response of the dam with a rigid and flexible foundation with and without mass were appraised. The results indicated that modal frequencies in the condition of with and without Pre-stress were different value in all cases. Moreover, the frequency of first four modes by increasing mass and decreasing the stiffness of foundation, frequencies in the case without initial condition (without Pre-stress) has a slightly increased and in the case with initial condition (Pre-stress) had considerable decrease.

Analysis of Seismic Behavior of Four-side Partially Connected Steel Plate Shear Wall

Four-side partially connected steel plate shear wall is the structure that frame and plate are incompletely connected. Through the analysis of mechanism, it shows that, when compared with traditional completely connected steel plate shear wall, the partially connected one causes less additional bending moment on frame. In order to further learn about the behavior of partially connected steel plate shear wall, this paper used FE modeling method on ABAQUS. The paper analyzed the influences of the frame-plate connection ratio and the height-thickness ratio of steel plate on the behavior of unstiffened four-side partially connected steel plate shear wall, and investigated the function of three different forms of stiffeners on partially connected steel plate shear wall.

Hollow block masonry wall reinforced by built-in structural configuration: Seismic behavior analysis

This paper proposes a new type of wall with built-in structural configuration. Common blocks with single-row holes serve as grouted recesses in the construction of built-in structural columns, core columns, and diagonal braces of the wall. The construction of this built-in structural scheme is more efficient and cost-effective than normal wall structures because it necessitates no formwork or large construction equipment. A nonlinear finite element analysis and integral modeling process were conducted based on horizontal cyclic loading tests of four hollow-block masonry walls with different built-in structural schemes. The feasibility of the model was verified by comparing the test and calculation results. The effects of different structural schemes on the failure process, failure mode, bearing capacity, stiffness degradation, and displacement ductility of the masonry wall were analyzed to determine the optimal structural details. The built-in structural columns and core columns should be concentrated at both wall ends while core columns are added in the center of the wall as necessary; a horizontal steel tie mesh can ensure cooperative bonding among structural columns and core columns. The effects of various strength grades of grouted concrete on masonry wall seismic performance with the optimized scheme were also observed.

Finite Element Analysis and ANFIS investigation of seismic behavior of sandwich panels with different concrete material in two story steel building

This study aimed to apply sandwich panel in a two-story steel building to improve its behavior. Sandwich concrete panels consist of three basic components including wires, insulating layer and concrete cover. This research studied the behavior of sandwich panels by changing the Young's modulus of the concrete with Finite Element Method and evaluated the displacement, acceleration, and panel stresses. According to the results, increasing the Young's modulus of the concrete, the frame seismic behavior was improved. Using sandwich panels instead of conventional brick increased the building resistance against seismic load while decreasing the structure drift and acceleration. Increasing the Young's modulus of the shotcrete layer enhanced the behavior of the seismic panel. In addition, the results showed that the two-story building, which comprised of sandwich panels, had an appropriate performance against the seismic load. Ultimately, ANFIS was used to predict the response of the building under seismic loads. The effects of some variables such as Young's modulus of concrete, variations on the elevation and panel’s number on displacement and acceleration have been presented.

Seismic Behavior Analysis Considering Soil Structure Interaction of RC Multistory Buildings in Halabja City

Response of structures to seismic loads measures the degree of safety of the structures. In order for buildings to be under a more realistic circumstance, it is essential to consider the effect of Soil – Structure – Interaction (SSI) in the analysis of the building subjected to seismic loads. In this study, three samples of typical buildings with six, eight and ten stories are chosen with and without the effect of SSI using both equivalent static method and dynamic response spectrum analysis. For each method, the five different soil categories (SA, SB, SC, SD, SE) are examined to illustrate the effect of the foundation soil on the buildings subjected to a seismic load. The results show that no modifications can be observed in rock foundations with or without the consideration of SSI. On the contrary, the effect on SSI can increase the displacement in low stiffness soils particularly soil type (SE). Similarly the natural time period of the buildings increase significantly with decreasing the soil stiffness.&nbsp

Investigation of concrete material models for analysis of seismic behavior of reinforced concrete under reversed cyclic load

Investigation of concrete material models for analysis of seismic behavior of reinforced concrete under reversed cyclic load

Seismic Behavior Analysis of Recycled Aggregate Concrete-filled Steel Tube Column

Seismic Behavior Analysis of Recycled Aggregate Concrete-filled Steel Tube Column

Comparative Analysis of Seismic Behaviour of Multi-Storey Composite, Steel and Conventional RC Structure

Comparative Analysis of Seismic Behaviour of Multi-Storey Composite, Steel and Conventional RC Structure

Experimental study on hysteretic model for L-shaped concrete-filled steel tubular column subjected to cyclic loading

L-shaped concrete-filled steel tubular (L-CFST) column can improve the space layout and can increase the utilization rate of the indoor space. It is a new type of structural column in civil engineering. At present, the research on seismic performance of L-CFST column is insufficient. In this paper, nine L-shaped concrete-filled steel tubular columns were subjected to cyclic loading to study the seismic performance, such as the hysteretic behavior, bearing capacity and stiffness. In the test, three parameters (slender ratio, axial compression ratio and steel ratio) were considered. Simultaneously, the regression analysis of the test results is carried out to establish the hysteretic model of the L-CFST column, and the authors proposed the calculation formulas on the model curve based on the parameters, i.e. load, displacement and stiffness degradation. The results of the hysteretic model of L-CFST columns are in good agreement with the experimental results, which provides a theoretical basis for the analysis of the non-linear seismic behavior of L-CFST columns.

Comparative Analysis of Seismic Behaviour of Flat Slab and Conventional RC Framed Structure

Comparative Analysis of Seismic Behaviour of Flat Slab and Conventional RC Framed Structure

Seismic Behavior Analysis of New Damping and Energy Dissipating Corrugated Steel Shear Wall System

In order to avoid the premature buckling of steel plate shear walls, the corrugated steel plate walls are used to increase stiffness and the buckling resistance performance, and soft steel dampers are also adopted to improve the energy dissipation capacity. This combined use of the corrugated steel plate wall and the damper leads to a new system: damping energy-dissipating corrugated steel shear wall (DCSW). A numerical simulation model was established to study the seismic behavior of DCSW using the software ABAQUS, in which the material and geometric nonlinear were considered. Based on that, the ultimate bearing capacity, stiffness and ductility were analyzed. The results indicate that the DCSW structure has a high strength redundancy. The strength of DCSW structure is about 18% higher than that of steel.

Analysis of seismic behaviour of an offshore wind turbine with a flexible foundation

This paper investigates the effects of nonlinear soil behaviours on the structural responses of offshore wind turbines (OWTs) subjected to wind, wave and earthquake loadings. A novel seismic analysis framework (SAF) is developed for the assessment of seismic behaviours of OWTs with flexible and fixed foundations. The SAF consists of an improved QuakeDyn module that is implemented into an open source tool (FAST). SAF has been validated through benchmark studies using numerical tools and the results show good agreements. Fully coupled nonlinear simulations have been performed for OWTs with fixed and flexible foundations under operational, parked and emergency shutdown states. The flexible foundation is modelled using nonlinear p-y curves obtained using LPILE. For all the examined operating conditions, notable differences of magnitude and variation in the responses between the flexible and fixed cases are observed, indicating the need for soil effects to be accounted in seismic behaviour analysis of wind turbines. It is further observed that the earthquake induces more severe vibrations on wind turbines with a flexible foundation compared to the one with a fixed base. Also, aerodynamic damping dissipates more energy from earthquake excitation resulting in a smaller tower-top fore-aft displacement. The shutdown triggered by the earthquake causes a 34% increase in the mudline bending moment for the flexible foundation case, while a decreasing trend is observed for the fixed foundation model. Similar observations are made regarding the tower-top displacements. The observations imply that ignoring the soil effect may lead to misjudgement of the consequence of an emergency shutdown. The relative orientation of the ground motion with respect to the wind direction causes significant difference in the seismic behaviour of the wind turbine. This confirms that it is necessary to interchange the horizontal components of an earthquake in order to consider the intersectional effect between ground motion and wind.

Seismic Behavior Analysis of Composite Buildings with Respect to RCC Buildings

Steel concrete composite construction has gained wide acceptance worldwide as an alternative to pure steel and pure concrete construction. The use of steel in construction industry is very low in Nepal compared to many developing countries. There is a great potential for increasing the volume of steel in construction, especially in the current development needs. Not using steel as an alternative construction material and not using it where it is economical is a heavy loss for the country. Use of composite material is of particular interest, due to its significant potential in improving the overall performance through rather modest changes in manufacturing and constructional technologies. Steel concrete composite construction means the concrete slab is connected to the composite beam with the help of shear connectors so that they act as a single unit. In the present work, steel concrete composite (both full and half composite) with RCC options are considered for comparative study of seismic behavior of 10 multistoried commercial buildings (4-storied, 5-storied, 6-storied, 7-storied, 8-storied, 9-storied, 10-storied, 12-storied, 16-storied and 20-storied which is situated in earthquake zone V and for earthquake loading, the provisions of IS:1893 (Part1)-2002 is considered. For modeling of composite and RCC structures, SAP2000 software is used. Steel-concrete composite construction system is an efficient, economical and innovative method for seismic resistance of multi storied buildings. Equivalent static method of seismic analysis is used in the analysis of models. Comparison of parameters like time period, axial force, shear force, bending moment, deflection, storey drifts, base shear, storey stiffness is done for full composite (beam-column both composite), half composite (column composite) and RCC structures. The results are compared and found that composite structure is better in several aspects.

Finite element analysis of seismic behavior of FRP reinforced concrete frame structure

A finite element model of FRP reinforced concrete frame structure is established to analyze the structural performance of FRP reinforced concrete frame. The load displacement hysteretic curve, skeleton curve and ductility of the AFRP reinforcement, CFRP bar and GFRP reinforced concrete frame model are analyzed. The results show that the bearing capacity of the CFRP reinforced concrete frame is the highest, and the AFRP coagulation is used for the concrete frame. The GFRP reinforced concrete frame is the smallest, and the reinforced concrete frame model with AFRP reinforcement is the best in the three types of FRP reinforced concrete frame models.

Comparative analysis of seismic behavior of RC buildings with Shape Memory Alloy rebar in regular, torsional irregularity and extreme torsional irregularity cases

SMAs (Shape Memory Alloys) have been implemented about a decade in design of the concrete buildings and improving their behavior. Among the major advantages of reinforced concrete structures with SMA one could refer to their super-elasticity property and the reversibility of inelastic displacements in the structure. In this article the seismic behavior of RC buildings with SMAs in regular, torsional irregularity and extreme torsional irregularity cases for three height types of building is investigated. For this purpose the effects of SMA as longitudinal reinforcement in structures with different number of stories (3, 6 and 9) which represented the Low, Mid and High-Rise buildings are examined. For each building, three reinforcement arrangements including the case of full Steel, the case of SMA at the plastic region of the beams and Steel reinforcement in other regions and also the case of SMA rebar over the entire length of the beams are taken into consideration. In all of the above cases, the Steel rebar is used in columns for economic purposes. In continuation, nonlinear dynamic time history analysis method was performed where the parameters of the maximum drift, residual drift, amplification factor, residual amplification factor, and base shear were investigated for each case of the mentioned buildings. The obtained results indicate that application of SMA in irregular buildings mitigates the devastative effects of irregularity, including reduction in the base shear and drift in buildings.