Earthquake Acceleration Research Articles

Design-condition-informed shear wall layout design based on graph neural networks

The construction industry, traditionally labor-intensive, has now been evolving towards automation and the incorporation of intelligence. Notably, the shear wall layout has been a critical component in structural construction, where neural networks have promoted the emergence of sophisticated design methods. These methods integrate graph neural networks (GNNs), successfully mitigating the computational resource demands and challenges in capturing the topological features, which are the impediments in pixel image-based methods. However, the existing GNN-based methods marginally accommodate structural design conditions and underperform in fulfilling practical engineering requirements. Specifically, these methods overlook influential factors such as the peak ground acceleration (PGA) of the design basis earthquake (DBE), characteristic ground period, and building height, all of which are crucial to the shear wall layout design. To address this research gap, this study proposes an innovative GNN-based design method that duly incorporates design conditions—including the PGA of the DBE, characteristic ground period, and building height—and rigorously evaluates its advantages over previous approaches. The findings confirm the efficiency and reliability of the proposed design-condition-informed method and highlight its capability to accurately correlate shear wall layouts with design conditions.

Dynamic analysis of historıcal masonry arch bridges

There are many historical bridges belonging to various civilizations in our country. Historical bridges also help us understand the sociological, economic and cultural structures of civilizations that lived between the past and the present. Historical bridges have been deformed due to natural events and human factors and some of them have been destroyed. It is extremely important to know the behavior of these bridges against earthquakes, since a large part of our country is located in a region with high earthquake risk. For this reason, the dynamic behavior of structures is examined with numerical and experimental studies, and earthquake analyzes are made using earthquake acceleration records obtained from past earthquakes or artificial earthquakes. In this direction, it is aimed to strengthen the weak aspects of the structures. For this reason, it is necessary to evaluate the behavior of historical masonry bridges that have survived to the present day in order to carry out restoration and protection. In this article, the historical Sultan Hamid I-II and III bridges in the Askale district of Erzurum province are discussed as a numerical application. These bridges were modeled in three dimensions using the SAP2000 finite element program. First of all, static analyzes of the bridges under their own weight were made. Then, the dynamic properties of the bridges were determined by making modal analyzes. After the dynamic properties of the bridges were determined, dynamic analyzes were made in the time period.

Seismic analysis of a soil-liquid tank system using MATLAB Simulink

In this paper, a model is proposed for analyzing the long-term responses of a liquid tank system to earthquake loads while taking soil interaction into account. Three degrees of freedom (DOFs) in the sway-rocking form and the monkey tail DOF are used to model the soil-foundation system, while the fluid in the tank is modeled as a 2-DOF lumped parameter using the substructure method. By using the MATLAB Simulink tool to numerically integrate the system of differential equations of motion, the response of the DOFs, shear force, and moment at the tank bottom can be tracked over time. The El Centro 1940 earthquake's acceleration excited a vertical cylindrical tank with a radius of 10 m and a water mass of 8 m; the results of the analysis show that the horizontal displacement of the convective mass increased by 16.36%, and the shear force and moment significantly increased in comparison to the case of the tank rigidly linked to the ground.

Stable node-based smoothed finite element method for seismic stability analysis of a square tunnel in cohesive-frictional soils

This paper presents a stable node-based smoothed finite element method (SNS-FEM) based on the upper theorem for stability analysis of a square tunnel in cohesive-frictional soils subjected to seismic forces and surcharge loading. The soil behavior is considered homogeneous Mohr-Coulomb with cohesion c, friction angle ϕ and unit weight γ. Using the pseudo-static approach, the horizontal kh and vertical earthquake acceleration coefficients kv are applied to the entire soil mass. Then, the square tunnel is subjected to horizontal and vertical surcharge loadings on the ground surface. The variations of the seismic stability numbers with the change coefficients kh have been investigated for different values of the cover depth-to-width ratio of the tunnel H/B, soil properties γB/c, and internal friction angle ϕ. Several numerical results of square tunnels have been investigated, showing that the SNS-FEM approach can demonstrate accuracy and efficient solutions. The seismic stability numbers results are presented in design tables and charts for engineers to use in the preliminary design stage of the square tunnel. Finally, the article investigates the effect of horizontal and vertical seismic acceleration components on the corrective coefficients of a square tunnel.

Settlement of combined piled raft foundation of a nuclear power plant in non-liquefiable and liquefiable soils

The settlement analysis of a nuclear power plant (NPP) resting on the combined pile raft foundation (CPRF) under static and seismic loads is very important. However, it has not yet been reported in the literature as most NPPs are founded on raft foundation rather than on CPRF. In this paper, the settlement has been examined in detail. The geometrical nonlinearity at the interface of raft-soil and pile-soil is considered using the coulomb friction. The piles are rigidly connected to the raft. The nonlinear behaviour of the soil in the non-liquefiable soil is modelled using elasto-plastic Drucker Prager cap model and CycLiq model for the liquefiable soil. For this, user defined material (UDM) is implemented in the FLAC3D material library. Thus, a complete 3D finite difference model of an NPP considering raft-pile-soil-structure interaction (RPSSI) for nonlinear settlement analysis is developed. After successful validation of the present CPRF, numerical model with the literature, it has been used for further study under real earthquake acceleration–time history. Next, CPRF with NPP structure is studied under static loading, which is further extended for the nonlinear time domain settlement analysis. The effects of variation in various parameters i.e., spacing between piles, cohesion, friction angle, and Poisson's ratio of soil on the settlement, are examined and found to be significant. The dominant frequency of the earthquake significantly affects the response of the CPRF. It was inferred that the interface nonlinearity has greater significance in the liquefiable soil as compared to the non-liquefiable soil. Higher differential settlement in the liquefiable soil is attributed to the reduction in the stiffness of the soil. The findings of this study could be useful to frame the general guidelines for the economical design of NPP-CPRF systems.

Displacements and stresses around a circular tunnel in an elastic medium with pseudo-static horizontal earthquake body forces

This manuscript presents an analytical solution based on the complex variable approach for computing displacements and stresses around a single circular tunnel in a linear elastic medium in the presence of pseudo-static horizontal earthquake body forces. The solution has been obtained with the imposition of uniform as well as non-uniform radial displacement boundary conditions along the tunnel’s periphery taking the ground volume loss (GVL) as a governing input parameter. The non-uniform radial displacements’ boundary condition along the tunnel periphery has been modelled by using the Gaussian distribution function. The effects of the distribution of the tunnel’s peripheral displacements, Poisson’s ratio of the continuum and the depth to radius of the tunnel on the results have been examined. Necessary validation exercise, in the presence of horizontal earthquake acceleration, has also been carried out by comparing the obtained results with that computed on the basis of the finite element method. The results were also compared with that reported in literature. It was observed that with an increase in the pseudo static acceleration, there is (i) a significant increase in the horizontal displacements, (ii) a generation of non-symmetric displacement and stress pattern, (iii) an increase in the shear stresses, and (iv) the development of high deviatoric stress zones around the tunnel periphery.

Seismic Bearing Capacity of Strip Footings Placed Adjacent to Rock Slopes

ABSTRACT The bearing capacity of strip footings placed adjacent to the rock slopes subjected to pseudo-static horizontal earthquake body forces has been investigated by using the upper bound (UB) finite element limit analysis (FELA) in combination with a mesh adaptive strategy. The generalized Hoek–Brown (GHB) failure criterion is applied to describe the strength properties of rock masses, which can be treated as its native form without the smoothing of the yield surface while employing the second-order cone and power cone programming to solve the optimization models. Based on the UB FELA method, the seismic bearing capacity factor is determined considering the effect of different governing parameters, namely the horizontal earthquake acceleration coefficient k h , the normalized slope height H/B, the rock strength ratio σ ci /γB, the geological strength index GSI and the material constant m i . For design purpose, a series of non-dimensional charts are provided, and typical failure mechanisms are also discussed in detail.

Effects of Diagonal Friction Dampers on Behavior of a Building

In this study, the effect of the friction damper location on the earthquake behavior of a building was investigated. Diagonal braced friction dampers were placed on different floors, and the changes in building behavior were examined. For this purpose, a scaled experimental building model with five floors, with a single span in the x and y directions, was used. Numerical model validation was carried out by taking into account the experimental and numerical period values obtained via the effect of free vibration. The period, peak displacement, and maximum shear force of the friction dampers, arranged in various configurations, were compared using the numerical model in conjunction with three different earthquake acceleration records. According to the investigations, the damper performance of the design changes depending on the earthquake acceleration that is affecting the building. Friction dampers located on the lower floors are more effective at reducing period, peak displacement, and floor shear forces than those located on the upper floors.

Review and comparison of different strategies to define earthquake design accelerations

AbstractIn the task of defining earthquake design accelerations, different approaches have been used worldwide and recent advances have led to changes in the rationale behind the choice of these coefficients. Considering that the two main objectives of earthquake engineering are to guarantee a certain level of earthquake safety while allowing designs to be feasible from an economic perspective, given the scarcity of resources, this paper reviews and compares different approaches that have been used to define the earthquake design coefficient, starting from the classic one, based on the selection of a fixed return period, and covering other more complex proposals that include, in one way or another, the physical vulnerability of the buildings. For each case, we assess how these two earthquake engineering objectives are addressed and review, from the coding perspective, their advantages and limitations. Our findings indicate that only one of these approaches, denoted as optimal design and proposed in 1976 by Rosenblueth, explicitly accounts for both earthquake safety and construction costs. We conclude that instead of aiming to have a uniform criterion to define the design accelerations (e.g., uniform return period or uniform collapse probabilities), an optimization criterion must be used, despite the challenges it presents from the perspective of building codes.

A suggested dynamic soil – structure interaction analysis

In this paper, a new methodology for time domain analysis of buildings on raft foundations considering soil – structure interaction is proposed. Sub-structuring technique is used to separate the building as super-structure and the underneath soil as sub-structure. The super-structure can be modeled using any numerical method. However, in this paper the super-structure is modeled via the BEM to consider the real interaction area between column and slabs. The dynamic load is considered as an earthquake acceleration record that can be transformed to equivalent dynamic loads acting on the super-structure floors. The sub-structure is analyzed using the dual reciprocity boundary element method as closed domain. New iterative coupling technique is proposed between the super and sub-structures to reduce the computational effort and required storage. An example is presented to demonstrate the strength and the practicality of the proposed methodology.

Soil-Structure Interaction of Retaining Walls under Earthquake Loads

The study is devoted to both static and earthquake response analysis of retaining structures acted upon by lateral earth pressure. Two main approaches were implemented in the analysis, namely, the Mononobe-Okabe analytical method and the numerical Finite element procedure as provided in the ready software ABAQUS with explicit dynamic method. A basic case study considered in the present work is the bridge approach retaining walls as a part of AL-Jadiriya bridge intersection to obtain the effects of the backfill and the ground water on the retaining wall response including displacement of the retaining structure in addition to the behavior of the fill material. Parametric studies were carried out to evaluate the effects of several factors such as vertical and horizontal components of the earthquake, maximum peak acceleration, angle of friction, damping ratio, height of the wall and groundwater level within the medium of fill. Three heights of retaining walls were considered for those above mentioned factors, these are (2.9m, 4.7m and6.7m). A comparison is made between the responses obtained on the basis of finite element analysis with those obtained using the Mononobe-Okabe method. It is found that the lateral wall responses obtained using the FE were larger than those calculated by the Mononobe-Okabe method for all heights of the retaining wall, it was also found that pore pressure of the ground water depends on the water flow through the backfill during the earthquake. The distribution of the dynamic earth pressure on the wall is nonlinear and depends on the earthquake ground acceleration in addition to the wall height and soil properties. Based on the numerical analysis and the results obtained from the parametric studies carried out, two expressions are proposed to evaluate the maximum lateral wall response in terms of wall height, soil properties and earthquake base excitation acceleration, and hence the dynamic earth pressure acting on the retaining structure.

Seismic stability analysis of 3D tunnel faces in unsaturated soils

This paper aims to develop a framework using the kinematic approach to assess the face stability of tunnels in unsaturated soils under seismic conditions, allowing for a rigorous upper-bound solution of the required face pressure. The stress behavior of the soil under steady unsaturated infiltration is analytically described using a suction stress-based framework. Three methods, i.e., the pseudostatic (PS) method, conventional pseudodynamic (CPD) method, and modified pseudodynamic (MPD) method are employed to represent the earthquake acceleration for the seismic analysis of tunnel face stabilities. The temporal and spatial variations of seismic accelerations and suction stresses are incorporated into the work-energy balance equation within the 3D discretization-based failure mechanism. A hybrid optimization routine is employed to search for the maximum required face pressure. The developed framework is validated through a comparison analysis with prior research, and the outcomes obtained from the three methods of representing seismic accelerations are compared. Several parameter analyses are performed to discuss the effects of the unit weight of unsaturated soils, dynamic characteristics, and hydraulic hysteresis. The framework can provide a useful tool for quantitatively analyzing the impact of potential seismic forces, as well as steady unsaturated infiltrations paired with hydraulic hysteresis, on the tunnel face stability.

Application of metaheuristic algorithms in prediction of earthquake peak ground acceleration

AbstractThe seismic resilience of a structure has been evaluated using peak ground acceleration (PGA). Ground motion parameters such as source characteristics, local site conditions are used to forecast the PGA of the ground motion. This paper aims to develop an Artificial Neural Network (ANN) based model to predict the PGA. Here, hypocentral distance (), shear wave velocity (), and moment magnitude (), are used as input parameters. The model uses 12,706 ground motion recordings from 283 earthquakes from the revised NGA‐West2 database supplied by Pacific Engineering Research Centre. Among the whole data, 70% of the data is set for training, 15% for validation, and 15% for testing the network. The R value derived from the testing dataset is 0.952, indicating the excellent performance of a network. An extensive parametric study is conducted with the PGA values, and the results indicate that the PGA increases with the magnitude and decreases with the hypocentral distance. The predicted PGA values from the present study are comparable with those from the existing relationships in the global database. The generated ANN model is further verified by comparing the predicted and recorded PGA values of an actual recorded event.

Investigating seismic behavior of a modified widened flange beam-column connection in SMRF utilizing experimental, numerical and hybrid simulation

This manuscript presents the seismic performance of a modified widened flange beam-column connection in a special moment-resisting frame (SMRF). The beam-column connection has been modified by two cover plates welded to the top and bottom flanges of the beam and investigated under earthquake acceleration. One-story one-bay special moment resisting frame with an increased beam flange at the vicinity of column was analyzed in accordance with the Iranian Code of Practice for Seismic Resistance Design of Buildings (Standard 2800). Experimental investigation was carried out in which a cyclic displacement history was applied. Numerical finite element analysis was carried out using ABAQUS and its results validated by experimental test results. A hybrid simulation was conducted utilizing OpenSees as the finite element software, OpenFresco as the middleware and LabVIEW as data collector and actuator motion controller. Results comparison of three above mentioned methods (experimental test, numerical analysis and hybrid simulation) indicate that the hysteresis curves are in great compatibility with each other. As expected, results demonstrate that the yielding occurred immediately beyond cover plates at arc shaped areas of beam. On the other hand, the experimental and numerical results show that the specimen reached at least 0.07 rad drift angle before experiencing strength degradation. Furthermore, parametric studies on ‘c’ and ‘R’ which are two key parameters of modified widened flange beam represent that for a constant dimensions of cover plate, increasing ‘c’ and decreasing ‘R’ will reduce plastic strain and stress demands in beam.

Numerical investigation of liquefaction-induced settlement and instability on earth dams

Liquefaction is a phenomenon in which soil loses its bearing capacity, large settlements occur, and lateral spreading and failures may be caused. Numerous studies around the world have shown that liquefaction occurs in the alluvium foundations of earth dams. In this paper, methods of assessment and numerical analysis have been used to assess the Shourijeh reservoir dam liquefaction. According to the latest criteria, it was observed that by considering the acceleration of the maximum credible earthquake (MCE) level, the alluvial foundation of the Shourijeh dam is liquefiable in some areas. The dynamic analysis and liquefaction modelling based on linear equivalent analyses have been used. By analysing the sliding block and sliding circles based on the limit equilibrium method and the Newmark sliding block analysis, the stability safety factors of slopes for the Shourijeh dam after the earthquake have been investigated for three different earthquakes and various states of reservoir water level. The results, in addition to providing helpful information regarding the performance of earth dams against liquefaction and its effects, have shown that the settlements caused by liquefaction in the studied dam are not so large that they would cause extensive damage of the dam at the MCE level.

Seismic Performance of Three Ancient Stupas in Anuradhapura, Sri Lanka

Ruwanweli, Abayagiri and Jetavana stupas situated in Anuradhapura, are three ancient wonders of Sri Lanka. Renovations and restorations of these stupas were started in early parts in the 20th century and carried out until recently. Considering their geometric proportions, cultural and social importance, there is an impending need to assess these stupas for seismic performance to avert any possible damages due to seismic activities that might occur in the future. Further, this requirement has become more important due to some researchers’ predictions on intraplate activities in the behaviour of ancient stupas with respect to possible earthquake accelerations. In this regard, two-dimensional numerical models of the three stupas were prepared using SAP2000 v.14: generalpurpose software package. Both static and dynamic analyses were performed on numerical models for self-weight and two recorded acceleration histories, respectively. Two acceleration histories are from Mahakandarawa, Sri Lanka and Manjil, Iran. Material parameters of ancient bricks were obtained from previous literature works and experimental test results conducted on similar bricks of another ancient stupa in Sri Lanka. Considering the past records of earthquakes that have occurred in Sri Lanka, it was understood that all three stupas are in the safe realm under magnitude 4.7 earthquakes (Peak Ground Acceleration of 5.48x10-5 g). Even referring to the stress distribution with magnitude 7.4 Manjil earthquake (Peak Ground Acceleration of 0.4 g), both Ruwanweli and Jetavana stupas are in safe zone.

Seismic bearing capacity of shallow foundations subjected to inclined and eccentric loading using modified pseudo-dynamic method

In this paper, a comprehensive parametric study is conducted to evaluate the seismic bearing capacity of shallow strip foundations overlying dry and cohesionless granular soil under the actions of inclined and eccentric loadings. For this purpose, a systematic combination of the lower-bound theorems of the limit analysis, the finite element method, and the nonlinear programming is implemented. The seismic loading condition is simulated by the well-established modified pseudo-dynamic (MPD) approach by accounting for the significant influence of phase difference as well as the primary and shear waves propagation through applying non-uniform inertia forces along the vertical and horizontal directions, respectively. Unlike the pseudo-static approach, in the so-called modified pseudo-dynamic loading, a more realistic dynamic nature of the seismic excitation is taken into account using various soil dynamic properties and spectral parameters of the problem under study. In this way, a more viable response of the shallow foundation subjected to seismic loading could be captured by simulating a visco-elastic material through the well-defined Kelvin-Voigt model. The modified pseudo-dynamic (MPD) method considers the influences of shear and primary wave velocities, amplification of earthquake loading, and period of lateral shaking. The current MPD approach is capable of considering the local site effects and damping characteristics of the soil deposit underneath shallow footing by adopting a non-uniform and nonlinear acceleration field inside the soil medium. The results of the seismic bearing capacity are presented in the forms of spectral responses and failure envelopes for the eccentric and inclined loadings. The results show that the failure envelopes of the shallow foundation subjected to either inclined or eccentric loading significantly shrink with the increase in the earthquake accelerations and decrease in the material damping of the underlying soil mass. The amount of changes in the size of failure envelopes in the normalized V-H and V-M spaces due to the variation of seismic intensity and material damping depends directly on the non-dimensional frequency of the earthquake excitation.

Development of the Amplification Factor Fa and Fv map based on the Earthquake Acceleration Map on ground surface and in Base Rock and Seismic Code

Development of the Amplification Factor Fa and Fv map based on the Earthquake Acceleration Map on ground surface and in Base Rock and Seismic Code

Study of potential for earthquake acceleration around NYIA, Kulon Progo based on the history of seismicity in Yogyakarta

The need for an international airport for the Yogyakarta area has been met with the presence of the new airport, New Yogyakarta International Airport, which is located on the coast of Kulon Progo Regency. The presence of the new airport had become a debate because of its location on Congot Beach and Glagah Beach. One of the debates is the link to vulnerability to earthquakes. This study is intended to determine the Peak Ground Acceleration (PGA) in the area around the airport to the sources of earthquakes that have occurred in the Yogyakarta and surrounding areas, so that the potential level of damage that can be determined. The research method used is to use data from the location of the nearest past earthquake and then calculate the acceleration using the PGA formula. The results of calculations with shallow earthquake sources and megathrust PGA values range from 0.05 to 0.189 gal. This value when converted to the MMI scale shows the V-VII scale.

Earthquake Hazard Mitigation for Uncertain Building Systems Based on Adaptive Synergetic Control

This study presents an adaptive control scheme based on synergetic control theory for suppressing the vibration of building structures due to earthquake. The control key for the proposed controller is based on a magneto-rheological (MR) damper, which supports the building. According to Lyapunov-based stability analysis, an adaptive synergetic control (ASC) strategy was established under variation of the stiffness and viscosity coefficients in the vibrated building. The control and adaptive laws of the ASC were developed to ensure the stability of the controlled structure. The proposed controller addresses the suppression problem of a single-degree-of-freedom (SDOF) building model, and an earthquake control scenario was conducted and simulated on the basis of earthquake acceleration data recorded from the El Centro Imperial Valley Earthquake. The effectiveness of the adaptive synergetic control was verified and assessed via numerical simulation, and a comparison study was conducted between the adaptive and classical versions of synergetic control (SC). The vibration suppression index was used to evaluate both controllers. The numerical simulation showed the capability of the proposed adaptive controller to stabilize and to suppress the vibration of a building subjected to earthquake. In addition, the adaptive controller successfully kept the estimated viscosity and stiffness coefficients bounded.