Earthquake Forces Research Articles

Proposed stress block for no coarse-aggregate concrete

Concrete is one of the materials in construction that continues to develop in strength and efficiency. Since most areas in Indonesia are vulnerable to earthquakes, the building structures must be more resistant to seismic forces. Increasing the concrete's strength might reduce the building structure's dimensions and weight, which will also reduced the earthquake force. One example of high-strength concrete is reactive powder concrete (RPC), an innovative concrete with small particle materials to fill in the space within the concrete so it can strengthen the concrete. Despite the advantage, there is still a lack of design provisions for this type of concrete. This research was conducted to analyze the stress-strain diagram curve and the compressive stress block for no-coarse aggregtae concrete. In this research, compression tests have been carried out on 100 mm × 200 mm cylinder samples with concrete compressive strength ranges from 28 to 76 N/mm2. Test results indicate that the actual curve of the stress-strain relationship for concrete without coarse aggregate is almost linear and shaped like a triangle with the maximum strain ranges from 0.006 to 0.008. The energy per unit volume ranges from 0.1175 to 0.3658 N/mm2 and the average force capture point is 0.62626 units. Based on the test results, compression stress block for no-coarse aggregtae concrete are proposed.

Building Design for Lateral Earthquake Forces on a Multi-Story Reinforced Cement Concrete (RCC) Structure Including a Shear Wall

Building Design for Lateral Earthquake Forces on a Multi-Story Reinforced Cement Concrete (RCC) Structure Including a Shear Wall

Application of Effective Earthquake Force by the Boundary Reaction Method and a PML for Nonlinear Time-Domain Soil-Structure Interaction Analysis of a Standard Nuclear Power Plant Structure

Application of Effective Earthquake Force by the Boundary Reaction Method and a PML for Nonlinear Time-Domain Soil-Structure Interaction Analysis of a Standard Nuclear Power Plant Structure

Comparative Analysis of RCC Structure with Energy Dissipation Device and Composite Structure

Abstract: The ground movement which occurred naturally and creates disaster to cause damage of the structures is called Earthquake. In the earth’s crust seismic activities occur that creates waves. These waves transmit to structures through foundation. Thus, due to this earthquake movements, inertia force is invoked in structure resulting in damaging the whole or part of structure. Base isolation is the recent development for seismic resistant designs, this may not be totally controlling the ground movement but helps in minimising the impact of ground movement. Base isolation enables in reduction of earthquake forces by lengthening the period of vibration of structure. Also, the structural response accelerations are less than the ground acceleration because of Base isolation.

Experimental study on horizontal pressure of column-supported concrete group silos under earthquake force

ABSTRACT The overpressure of silo wall caused by granular materials under earthquake is one of the main reasons of silo damage. Two shaking table model tests were carried out with column supported silos and independent single silos, respectively. The seismic response of silo granular materials was analyzed first, and then the dynamic lateral pressure of silo wall under different levels of earthquake and overpressure coefficient were obtained. The results showed that the interaction between the granular materials and the silo wall in the group silos is related to the position of the individual silo. The seismic response of granular materials is linked with the spectral characteristics of seismic waves. The overpressure coefficients of the corner silo and the side silo are greater than that of the independent single silo with a 7% and 9% higher value, respectively. Apparently, the seismic response characteristics of the independent single silo are totally different from that of the group silos. It was concluded that when designing the wall of the group bin, the position of the bin should also be considered.

Earthquake Effects on Slope Stability by Using Finite Element Method. Case Study: Brazzaville City, Republic of Congo

The slopes are affected by the variations of slope gradient combined with the driving forces including external actions such as earthquake forces, producing shear stresses in the slopes, which are opposed to the soil shear resistance. Therefore, landslides are one of the most important worries on the social and economic viewpoint and for the quality of life of a local people. The present study is carried out in Brazzaville City, Republic of Congo where the region in its southern part is recognised to be geologically active, due to its tectonic background which has some influence on surrounding slopes or embankments. Then, it was used the shear strength reduction method to assess the slopes stability by using pseudo-static and static methods. Effects of various parameters on slopes stability are discovered by achievement of numerous analyses. Two magnitudes effects of earthquake on slopes stability for different height, slope gradient and shear resistance parameters were assessed by using the finite element code. Slope stability was evaluated considering its factor of safety from the usage of strength reduction method.

Seismic Evaluation of RC Building with Vertical Setbacks as per IS1893 (Part 1):2016

Earthquake forces are the least predictable and most devastating form of forces. These forces are not only responsible for loss of economy, property and material but possess a huge threat to lives of people as well. In past several years, severe damages to buildings and causalities have been witnessed due to these disastrous forces there by challenging the designing and construction authorities. Many buildings are designed with vertical setbacks due to architectural, functional or economic reasons wherein fewer stories in a building are wider than rest of the building. Such setbacks in buildings cause sudden jump in seismic forces at the level of discontinuity due to change in stiffness, mass and strength distribution along height. This might lead to torsion in the building under seismic forces. Structures incorporating vertical irregularities need to be studied for their behavioural aspects, identifying the weak links which might trigger the collapse. In the present study, effect of vertical geometric irregularities in a building is studied with respect to a regular building using equivalent static method and response spectrum method as per IS1893 (Part 1): 2016. The results obtained are compared in terms of displacements, storey drift, base shear, forces, modal time period, modal mass participation factor and % increase in structural members along with concrete quantity.

Performance-Based Design of an Irregular RC Structure with and without Supplemental Damping

Many countries are undertaking changes in earthquake design codes, the main reason for it is that the existing building codes do not specify the performance criteria of individual structural elements under various levels of shaking. Even though some buildings performed well in life safety aspects, many of those failed in safeguarding the building from high extent of structural damage under severe shaking. Retrofitting had also proved to be uneconomical for the buildings to perform better under severe shaking. In the current earthquake codes, the displacements and forces are within the elastic limit i.e., the assumed behaviour is linear. But the response of a structure to the major earthquakes is not elastic. There is a high chance of yielding and the development of plastic hinges in the members. Therefore, it is required to perform the non-linear analysis for assessing the inelastic behaviour of the structure. In the present study non-linear static analysis was adopted to assess the seismic performance of an irregular building in plan with re-entrant corners using the capacity spectrum method. If either the drift limit of the structure or the response of the hinges is exceeding the desired level of performance, the structure is fed with supplemental damping to ensure the required performance. It was observed that the formation of hinges crossed life safety level and entered the collapse prevention state. As the response exceeded the desired level of performance a methodology to calculate the required supplemental damping for the structure is proposed. Depending on the level of safety of the structure, an appropriate supplemental damping value can be obtained from the proposed performance plots.

Design of Metallic Dampers and Analysis Using MATLAB Program

Earthquakes are one of the major natural hazards to life on the earth and have affected countless areas on almost every continent. The damaged caused by earthquakes are mostly seen in man-made structures which are most of the time responsible for most of the causalities. Therefore, it is necessary that design of structures is done to resist earthquake forces, in order to reduce the loss of life. Passive control devices were developed earlier and have been used extensively in practice. Metallic dampers, one of the passive damping devices, dissipate seismic energy through in-elastic deformation of metals. It utilizes the yielding of metals as the dissipative mechanism. In the present study, characterization of ADAS (Added Damping Added Stiffness) type metallic damper is carried analytically and experimentally to understand cyclic behaviour. It is found that response of metallic damper is a function of its geometry and its mechanical characteristics of the metal. The primary factors affecting ADAS element behaviour are device’s elastic stiffness, yield strength and yield displacement. Attempt has been made to develop design procedure for ADAS type metallic damper in Indian Scenario. Designed damper behaviour is analysed by programming tool MATLAB obtaining solution of equation of motion for different time history data.

RESPON STRUKTUR AKIBAT PENEMPATAN DILATASI PADA BANGUNAN DENGAN KETIDAKBERATURAN HORIZONTAL

The placement of dilation in the building structure with horizontal irregularity causes a different response to the structure during an earthquake, because the structure is divided into several individual structures that stand alone so that they are different from the original structure. The proper placement of the dilation in a building will reduce the risk of collapse of the building during an earthquake as well potentially making structures simpler and more efficient. This study uses the design analysis method to compare the earthquake shear force, structural response, and internal forces in the structure due to the placement of the X-direction and Y-direction Dilatation. greater than the X direction dilatation, which is 42% in the X direction and 38% in the Y direction. The deviation that occurs in the Y direction dilation is greater than the X direction dilatation. X, but the internal force due to the Y direction of dilation on the beam is greater than the X direction dilation placement. So that the use of the Y direction dilation is slightly better than the use of the X direction dilatation in several things, such as the earthquake force and the inner force on the smaller column.

Comparative Seismic Analysis of High Rise Buildings with Different Structural Framing

Now a day it has been observed that modern trend is towards taller and slenderer structures both residential and commercial increasing rapidly. As the height of structure get increases, the building acts as cantilever and get deflected because of its slenderness. For such structure the effects of lateral loads like winds loads, earthquake forces have become more effective which increasing importance for every designer to face with the problem of providing adequate strength and stability against lateral loads with economic consideration. From the previous studies, it has been concluded that there was not much problem in drift failure particularly in lower seismic zones. But as we go to higher zones than the ordinary multistory buildings also face the problem of drift more than the prescribed by the IS code 1893-2002 which become critical limit causing sudden collapse during earthquake. This study focuses on the various provisions to reduce the drift of building and make it more stable. Some of them are providing shear wall, tube structural system and base isolation system. The analysis has performed using ETABS for G+42 multistoried building in zones III.

Behavior of Building Structure Subject to Tsunami Load

This study aims to analyze of the structural behavior of two-story building under the combination of earthquake forces and tsunami hydrodynamic forces, with model variations included the percentage of wall’s opening and thickness. The 3-D modeling of two-story buildings were conducted in this study using software SAP 2000; the first model consisted of wall panels with the percentage of openings of 0% (PD0), 25% (PD25), 35% (PD35), and 50% (PD50), while the second model included buildings with 150 mm and 250 mm wall thickness. In addition, the hydrodynamic force predicted by numerical simulations based on Smoothed Particle Hydrodynamic (SPH) was compared to that of predicted by semi-empirical design equations. The results of the wall panel modeling show that the greater the percentage of wall’s opening, the smaller the hydrodynamic load that can be carried out by the structure and hence, the lesser the stresses on the wall. The increase of building’s wall thickness from 150 mm to 250 mm under the combination of earthquake and tsunami loads decreased the stress on walls, moments and transverse forces. Conversely, the tensile and shear stresses on the walls were increased due to the combination of tsunami loads. The comparison of hydrodynamic force shows that the maximum force predicted by SPH was generally higher to that of predicted by the semi-empirical design equations.

A Review: Dynamic Analysis for Controlling Seismic Response of R.C. Frame Structure by Virtual Work

Abstract: The Performance of The RCC Building During Earthquake Depends Upon the Distribution of Stiffness Amongst The Storeys. If The Distribution Is Non- Uniform To A Large Extend, The Performance of The Building is Poor. The Storey Stiffness is Contributed By The Columns As Well As The Brick Infill. If The Effective Storey Stiffness of A Floor is Less Than 70% of the Storey Above Or Below It , Then It Is Called The Soft Storey. It Is Learnt From The Past Earthquakes That Soft Storey Are More Vulnerable To Failure. The Study of Building Performance During Past Earthquakes Has Revealed That Maximum Failures Have Occurred In The Parking Storey. Most of the buildings were damaged and collapse during in strong earthquake hence we will have to confirm safety against the earthquake force that are affecting the structure, and determine seismic responses of such building. In this project we will analyse the G+5 building through response spectrum analysis to develop the economic design. Computer software’s are also being used for the calculation of forces, bending moment, stress, strain & deformation or deflection for a complex structural system.

Dynamic Response of Deepwater Pile Foundation Bridge Piers under Current-wave and Earthquake Excitation

Pile foundation bridges are structures extending in the middle of the sea, so they are subject to currents, waves, and earthquake forces. This article presents a hybrid simulation that was used with input excitations of different current velocities, wave properties, and earthquake amplitudes to assess the non-linear dynamic behavior of pile foundation bridge piers. Based on the interface between MATLAB and ABAQUS software, the general formulations of fluid-structure interaction (FSI) under combined current-wave and earthquake loads are derived. Hydrodynamic and earthquake loading is consistently introduced by creating synthetic time histories of combined current-wave actions and spatially variable ground motion. The behavior of the dynamic model of a deepwater pile foundation bridge for the Songhua River in northeast China was adopted as an example of the study. The accuracy of the created model was verified using prior experimental and analytical computations. It is demonstrated how both linear and nonlinear dynamic behavior performs at various water depths under coupled current-wave-earthquake loading conditions. Revealing interesting aspects, particularly in terms of relative displacement, acceleration, shear, and moment response are shown. The results showed that the hybrid model is an efficient of simulating accurate predictions of the hydrodynamic pressure during earthquake actions for structures in coastal areas.

Seismic analysis of a G + 3 confined masonry building with AAC infill using SAP 2000

With increasing seismicity worldwide, there is a need for resilient structures that will withstand large earthquake forces. In this context, Autoclaved Aerated Concrete (AAC) blocks with Confined Masonry present an attractive option due to their light weightiness among other desirable qualities. Confined Masonry (CM) construction offers enhanced seismic resistance compared to unreinforced and non-engineered reinforced concrete frame construction and is preferred in high seismic zones. This study verifies the effectiveness of Confined Masonry construction with AAC blocks as infill material by modeling a 2D single-bay G + 3 frame in SAP2000. After the mesh convergence study and validation with existing results, the columns were checked as per IS 456 (2000) along with the stress and strain to ensure that they were within the linear limits of the AAC. The analysis is carried out for AAC infill thicknesses of 120 mm, 150 mm, and 200 mm for zones II, III, IV, and V as per IS 1893 (part 1) 2016. The result of the study is compared with 120 mm infill thickness in zone II as the base case.

Seismic Stability Analysis of Caissons under Earthquake Forces Considering 3D Log-Spiral Failure Surface

Bridge failure is mostly caused by geotechnical failure. Because caissons are the automatic choice for foundation systems for marine structures, such as bridges and wind turbines, this study addresses the determination of seismic passive earth pressure coefficients for caissons. In the present study, a realistic three-dimensional (3D) failure wedge was assumed to be formed behind caissons of different widths on the basis of the past results of experimental and numerical studies. The limit equilibrium method of analysis was adopted to determine the seismic passive earth pressure coefficients due to the cohesion component, surcharge component, and unit weight component. The current study takes into account the relative width and depth of the geotechnical structure and returns a series of design charts and tables for different soil-soil friction angles, soil-wall friction angles, and horizontal and vertical seismic acceleration coefficients. The results were compared with previous experimental and theoretical studies and found to be in excellent agreement.

Effect of replacing the lead core with rubber on the mechanical properties of lead rubber bearing

The expansion of earthquake zones over the past decade motivates scholars and researchers to find appropriate solutions to reduce demolishing and disaster risk. Base Isolation is one of the modern engineering solutions to dampen the earthquake force transmitted to the building. This paper estimates the effect of replacing the lead core of a lead rubber bearing (LRB) with the same size of rubber core on the mechanical properties of the seismic isolator using Finite Element Analysis (FEA). The Mooney-Rivlin was used to define the rubber hyperelastic and the Mullins effect was used to determine the rubber damage. The isolator, 700 mm in diameter with a lead core of 200 mm, using 24 rubber shims of 10 mm thickness, was simulated from a manufacturing company brochure. The shear strain of 150% was adopted with 3 hysteric loops for each model. Results presented that the rubber core increased 22% of the horizontal stiffness but decreased 5% of both horizontal force and stability. The Mullins Effect presented the rubber damage behaviour without a hysteresis loop, in which the horizontal stiffness had reduced because of rubber damage.

Seismic stability of a circular tunnel in cohesive-frictional soils using a stable node-based smoothed finite element method

This paper presents the effect of horizontal and vertical earthquake force on the stability of a single circular tunnel in cohesive-frictional soils using a stable node-based smoothed finite element method (SNS-FEM). In this study, seismic forces are computed as horizontal and vertical pseudo-static body forces arising on the soil and additional inertial forces associated with the uniform surcharge applied to the ground surface. In the upper bound limit analysis based on SNS-FEM, the soil behaviour is described as rigid-perfectly plastic materials, and plasticity deformation obeys the associated flow rule following the Mohr-Coulomb failure criterion. Firstly, the numerical results were checked against other numerical solutions in the literature. The present results agree with prior contributions, proving that the proposed approach can give efficient and reliable solutions to the stability number. Secondly, the variations of the seismic stability number with changes in the horizontal earthquake acceleration coefficient were intensively investigated for different values of soil properties, internal friction angleand the depth-to-diameter ratio of the tunnel. It is shown that the seismic stability numbers of circular tunnels reduce remarkably with the increase of horizontal seismic coefficientand the soil weight. Thirdly, the seismic stability numbers were summarised in design charts for practical use in geotechnical engineering.

Investigation of material deterioration and seismic behavior of Fertek and Hançerli Churches in Cappadocia Region

Cappadocia is among the rare natural and cultural centers on earth with its fairy chimneys, underground cities, rock churches, stone structures and natural beauties. Among these structures, Fertek and Hançerli Churches that are subjected to the scope of the study are very original artifacts with their superior construction techniques and rich workmanship according to the period they were built. In this study, the architectural features of Fertek and Hançerli Churches which were built in the 19th century and located within Niğde province in the Cappadocia Region were defined and material deteriorations were determined. In the light of these determinations, the existing static properties of these structures were examined using the Dynamic Finite Element Analysis program. Discoloration, vegetation, crack formation, moisture problems and partial mortar and stone losses were detected in both church structures. When the analysis results are evaluated, it has been determined that the structures need repair and improvement, depending on the region and soil class, considering the earthquake forces.

PERFORMANCE EVALUATION OF 34 FLOORS BUILDING STRUCTURE IN SURABAYA BASED ON SNI 1726:2012 AND SNI 1726:2019

Indonesia has undergone several earthquake regulations updates, starting from Peraturan Muatan Indonesia 1970 to SNI 1726:2019. This update requires earthquake loads with a larger return period. This has an impact on the existing buildings that were planned to use the old regulations. It is feared that the building does not meet the requirements required by the new regulations, so a review of the performance of the building is needed. This research will use a case study of a Cornell apartment building with 34 floors in the city of Surabaya, which is planned based on SNI 1726:2012 with concrete regulations SNI 2847:2013 and will be evaluated with SNI 1726:2019. The analysis uses Performance Based Design with the Nonlinear Time History Analysis method which was carried out in the 2016 ETABS program. The background to the use of the Performance Based Design method is its use which is quite easy to apply and can also be used to measure the efficiency of the structure being reviewed. The use of Nonlinear Time History Analysis is based on the fact that the use of this method has been regulated in SNI 1726:2019 and the use of this method is considered closest to the actual conditions in the field. Nonlinear Time History analysis in this study uses time history data from the Chichi earthquake in Taiwan in 1999. The evaluation of building performance is based on the performance level refer to FEMA 356. The results of the case study on the comparison of the two regulations show that there is an increase in the basic earthquake force by 1.02%. Meanwhile, in relation to drift ratio analysis, an increase of 1% on the X axis and 5.5% on the Y axis is obtained.