Standard Response Spectrum Research Articles

Response Spectrum Analysis of Multi-Story Shear Buildings Using Machine Learning Techniques

The dynamic analysis of structures is a computationally intensive procedure that must be considered, in order to make accurate seismic performance assessments in civil and structural engineering applications. To avoid these computationally demanding tasks, simplified methods are often used by engineers in practice, to estimate the behavior of complex structures under dynamic loading. This paper presents an assessment of several machine learning (ML) algorithms, with different characteristics, that aim to predict the dynamic analysis response of multi-story buildings. Large datasets of dynamic response analyses results were generated through standard sampling methods and conventional response spectrum modal analysis procedures. In an effort to obtain the best algorithm performance, an extensive hyper-parameter search was elaborated, followed by the corresponding feature importance. The ML model which exhibited the best performance was deployed in a web application, with the aim of providing predictions of the dynamic responses of multi-story buildings, according to their characteristics.

Improvement of Response Spectrum Analysis Method of Crane Pile Mooring Facilities

In this study, we analyzed the problems of the conventional response spectrum analysis method. Thereafter, we derived methods to improve it by considering the dynamic behavioral characteristics of a pile-type mooring facility with a crane. The applicability of the standard design response spectrum analysis method of crane pile mooring facilities was analyzed, and the results of previous studies on dynamic behavioral characteristics were reviewed to derive improvements and the applicability of the derived improvements in practice. when the analysis was performed with the application of the improvement, the stress of the pile during the earthquake was 70% of that of the conventional method. As a result of the study, in the recent trend where more stringent seismic design standards are required, applying the derived improvements will enable a more precise analysis than the conventional method, and reduce unnecessary costs of seismic retrofitting, contributing to the improvement of cost efficiency.

On the dynamic response of rectangular liquid storage structure subjected to blast-induced ground shock

The paper aims to investigate the dynamic response of the rectangular liquid storage structure (LSS) under blast-induced ground shock. A two-way fluid–structure interaction (FSI) finite-element model was established, and its effectiveness was verified using a laboratory experiment conducted on an explosion shock and vibration simulation platform (ESVSP). The relationship between the mode shape and frequency was explored using modal analysis. Higher-order modes are characterised by more half-waves preferentially forming in the short sidewall and adjacent sidewalls vibrating in the same direction. The sensitivities of the deflection, hydrodynamic pressure, and equivalent strain in relation to the peak, duration, and loading direction of ground acceleration (i.e. PGA, TGA, and DGA) were highlighted. The results showed that the LSS response magnitude increases linearly as the PGA increases, whereas it first increases and then decreases as the TGA is extended. Furthermore, a feasible method for building a standard shock response spectrum (SRS) was proposed, in which the ground-shock effects were divided into mitigation, enhancement, and equality regions. It is beneficial to evaluate the extreme value of the LSS response to ground shock. The LSS vibration is dominated by different modes as the DGA is varied. The deformation mechanism was revealed by considering the boundary conditions and force characteristics. The conclusion indicates that the bottom middle of the sidewall, as a weak link, needs to be protected.

Comparison of the Seismic Responses of an Arch Dam under Excitation from the Design Response Spectrum in the New and Old Chinese National Standards

The new Chinese national standard, Standard for the seismic design of hydraulic structures (GB51247-2018), has been published. Compared with the Specifications for the seismic design of hydraulic structures (SL203-1997), the standard design response spectrum curve was revised in the new national standard. In order to compare the seismic responses of an arch dam under excitation from the design response spectrum in the new and old standards, the dynamic calculation of a 240 m high arch dam is carried out by a three-dimensional finite element method. In the dynamic calculation, the B-differentiable equation is used to simulate the tension motion of arch dam contraction joints, and the multi-transmitting boundary method and the Westergaard added mass method are used to simulate the dam–infinite foundation and dam–reservoir interactions, respectively. The results show that the dynamic stress responses of the arch dam under excitation from the design response spectrum in the new standard are increased compared with those of the old standard. The seismic safety of an arch dam may decrease under excitation from the design response spectrum in the new standard. Thus, the seismic validation on built arch dams should be carried out by using the new standard when it is possible.

Preliminary strong ground motion simulation at seismic stations within nuclear power plant sites in South Korea by a scenario earthquake on the causative fault of 2016 Gyeongju earthquake

Stochastic and an empirical Green's function (EGF) methods are preliminarily applied to simulate strong ground motions (SGMs) at seismic stations within nuclear power plant (NPP) sites in South Korea by an assumed large earthquake with MW6.5 (scenario earthquake) on the causative fault of the 2016 Gyeongju earthquake with MW5.5 (mainshock). In the stochastic method, a ratio of spectral amplitudes of observed and simulated waveforms for the mainshock is assumed to be an adjustment factor. In the EGF method, SGMs by the mainshock are simulated assuming SGMs by the 2016 Gyeongju earthquake with MW5.0 (foreshock) as the EGF. To simulate SGMs by the scenario earthquake, a ratio of fault length to width is assumed to be 2:1 in the stochastic method, and SGMs by the mainshock are assumed to be EGF in the EGF method. The results are similar based on a bias of the simulated response spectra by the two methods, and the simulated response spectra by the two methods exceeded commonly standard design response spectra anchored at 0.3 g of NPP sites slightly at a frequency band above 4 Hz, but considerable attention to interpretation is required since it is an indirect comparison.

Dynamic analysis of biogas tank

Global warming is a phenomenon that makes us increasingly aware of the importance of protecting nature. Lack of drinking water and waste disposal belong to today’s biggest problem. This is the main reason why we try to recycle, use more renewable energy sources and treat waste ecologically. Drinking water tanks, sludge tanks for wastewater treatment and also tanks for biogas production, so-called fermenters, are becoming gradually more important. For built-up areas, respecting space usability, it is more appropriate to design tanks with a rectangular floor plan (so-called rectangular tanks). We can also use a system of rectangular tanks and thus achieve the most efficient use of space that is intended for them. In this article will be determined whether the proposed rectangular tank, intended for biogas production, has bearing capacity for dynamic loads. Construction of the tank itself must respect the design of the structure, as well as the building material, in order to prevent damage to its structure caused by the filling (it may also contain substances that could contaminate the environment and groundwater). This will ensure the integrity and load-bearing capacity of the tank and there is no risk of leakage. Selected tank is loaded with a standard response spectrum to see how it deforms, using finite element analysis in program ANSYS.

Three-dimensional linear seismic analysis of normal concrete gravity dam

The three-dimensional linear finite element model is established for the bottom outlet dam section of concrete gravity dam. Mode-superposition response spectrum method and the massless foundation time history method are adopted to analyze the static and dynamic comprehensive stress response and displacement response of the dam under the action of the standard response spectrum of the design earthquake or the corresponding artificial wave under the action of design earthquake and check earthquake. The results show that the dam works well in seismic condition. In addition, the influence of radiation damping of infinite foundation on the dynamic response of the dam section under different seismic waves is analysed. By comparing the dynamic and static comprehensive stress changes of the dam, it shows that after considering the radiation damping effect of the infinite foundation, the dynamic response of the dam body is significantly reduced.

Study on standard response spectrum parameters of special long-period ground movements

Multiple earthquake damages show that the long-period ground movements have an amplification effect on the dynamic response and seismic damage of long-period structures. To form an improved code design spectrum suitable for long-period ground movements, the standard response spectra consisting of four segments for near-fault pulse-like (NFPL) and far-field harmonic (FFH) ground movements are proposed. Firstly, two types of special long-period ground movements with reliable information are selected for this research. Then, the fundamental period of a single-degree-of-freedom (SDOF) system is extended to 16 s with the damping ratio of 5 %, and the seismic response spectrum and the normalized response spectrum are analyzed. Next, the normalized acceleration spectrum of long-period ground movements is calibrated to the standard response spectrum of regular variation. Finally, the parameters of standard response spectrum about long-period ground movements and the ones of the current code design spectrum are discussed. The results show that the current code design spectrum overestimates the structural seismic response in the short period under NFPL and FFH ground movements, while it underestimates the structural seismic response in the long period. The fundamental period of a SDOF system of china’s current code design spectrum should be extended to consider the influence on long-period structures acted by a long-period earthquake. Further, it accounts for the resonance effect of long-period ground movements which ensures the seismic design safety of long-period structures.

A preliminary proposal towards the revision of Indian seismic code considering site classification scheme, amplification factors and response spectra

This paper aims to improve the site classification scheme and amplification factors for the Indian Seismic Code. The present code IS 1893 (1):2016 ignores the amplification of effective peak ground acceleration due to the existence of soft soil layers. This results in lower design spectral accelerations on soil sites compared to those adopted by codes in other nations. 124 well documented sites from India are considered for ground response analysis using the equivalent linear procedure of DEEPSOIL. Time histories recorded from India and abroad are made spectrum compatible with the Type I spectra of Indian code, corresponding to all the seismic intensities with Effective Peak Ground Acceleration of 0.1 g, 0.16 g, 0.24 g and 0.36 g. Statistical methods are used to construct mean, mean plus standard deviation and mean minus standard deviation response spectra and amplification factors for the sites considered. Before the statistical analysis, each amplification factor curve is normalized with the effective site period (Tg) which exhibits a “characteristic peak at values of T/Tg not far from 1”. Normalized acceleration response spectra as well as period dependent soil amplification factors and equations are proposed for the new classification system. It is observed that the stratigraphy, impedance contrast, sediment thickness and site period play an important role in determining the soil amplification factors and therefore, should be considered in the future site classification schemes of the Indian Seismic Code.

An application of the transfer matrix approach for a dynamic analysis of complex spatial pipelines

An effective method for the calculations of stress and residual strength of complex spatial pipelines at static and dynamic loading with taking into account the vibration of internal liquid and Puasson coupling is presented. It based on the well-known transfer matrix approach. The method utilizes the exact mechanical equations for the stress-strained state of straight beam with distributed mass, which connect unknown parameters of forces and displacements at the end of beam calculation element with the parameters at the beginning of the element. At a general level, the solution scheme and calculation models are the same for static and dynamic calculations, the only difference – are the equations. Two different methods are used to find natural vibration frequencies of the distributed mass system: straightforward (“brute force”) and quick, based on Williams-Wittrick frequencies counter. Within such counter a special procedure is developed for taking into account fluid vibration with consideration of volumetric balance condition at T-nozzles. The excellent accuracy of the method is demonstrated by the modeling of thin-walled, water filled pipe behavior after the rod impact. Two seismic analysis procedures are implemented on the base of developed method: standard response spectrum procedure and normal-mode summation procedure (“exact” dynamical), which uses accelerograms. These methods and procedures have been already implemented in calculation software for pipeline strength assessment with the possibility of building of arbitrary complexity models by the user-friendly, visual way. Their effectiveness is demonstrated by the seismic calculation for primary circuit pipings of Zaporizhia NPP.

An Artificial Seismic Wave Suitable for Suspended Converter Valve in the UHVDC Transmission Project

The finite element model of suspended converter valve in an UHVDC transmission project with characteristics of flexible is constructed, and its vibration characteristics are simulated and analyzed firstly. The results show that this kind of suspended converter valve has obvious long-period character. Secondly, the long period phase of standard response spectrum in Code for Seismic Design of Buildings (GB50011-2010) is modified, and then the artificial seismic wave is synthesized employing the triangular series method. The result shows that this artificial seismic wave has long-period character. Finally, the time-history seismic dynamic simulation of the converter valve is done, and the seismic responses of the converter valve excited by three kinds of seismic wave with different period characters are compared and analyzed. The results show that the swing and stress of the suspended converter valve are larger under the long-period seismic wave synthesized in this paper. The quasi-resonance damage caused by long-period seismic wave should be concerned specially in the actual UHVDC transmission project.

The Mechanical Behavior of Ribs in Masonry Groin Vaults Subjected to Seismic Load

ABSTRACTHistorically, the first groin vaults were built without ribs, but ribs later appeared for various reasons. Some ribs have only an aesthetic role, while others have a clear structural role in stiffening the groin. The stiffening effect on the static behavior is currently of wide interest, as the preservation of architectural heritage has become important. While static behavior has various explanations, the discrete spatial structure of cross vaults allowed for only approximate solutions to dynamic problems, such as seismic load response. In this article, a 3D time-history analysis is carried out with a commercial discrete element code. Following the motion of elastic discrete blocks in the structure allows the continuation of nonlinear effects from the rocking and sliding of the blocks. The analysis only addresses the most presumably dangerous direction of ground acceleration. The time-history analysis uses a synthetic accelerogram; a real accelerogram is scaled in the frequency domain to fit to a standard response spectrum. The influence of the supporting walls is handled approximately by considering them to be an SDoF system, which affects the signal of the support acceleration.

Influences of the duration and frequency content of ground motions on the seismic performance of high-rise intake towers

Abstract The main purpose of this study is to investigate the influences of the duration and frequency content of ground motions on the seismic performance of high-rise intake tower considering structures-reservoir-foundation interactions. Thirty earthquake records matched with the standard design response spectrum according to Chinses code for seismic design of hydraulic structures of hydropower project were selected as ground motion input. The nonlinear seismic responses were classified according to the duration to investigate the effects of ground motion duration; while the nonlinear dynamic response under other fourteen earthquake records matched with previous standard design response spectrum with different response spectrum curves and characteristic periods were compared to study the effects of frequency content. The results show that the duration and frequency content in the seismic input can have significant effects on the seismic performance of high-rise intake towers.

On the Applicability of the Standard Response Spectra to the Seismic Hazard Assessment

The ground layer response to seismic loading is analyzed in the paper. Two approaches to the site profile behavior are considered: elastic (linear) and viscoelastic (equivalent linear modeling). Four typical soil profiles are taken into account; input peak values are within the range from 0.1 to 0.6g. In all profiles, when ignoring the nonlinear behavior, the calculated impacts are still within the standard response spectrum. When the nonlinearity is taken into account, the pattern is completely different. The standard spectrum is abundantly conservative for high frequencies; meanwhile, it substantially underestimates the level of hazard at low frequencies. Therefore, the shape of standard spectra as a whole does not adequately describe a seismic hazard, especially when the input signal is higher than 0.2g.

Predictive model for site specific simulation of ground motions based on earthquake scenarios

SummaryA predictive stochastic model is developed based on regression relations that inputs a given earthquake scenario description and outputs seismic ground acceleration time histories at a site of interest. A bimodal parametric non‐stationary Kanai‐Tajimi (K‐T) ground motion model lies at the core of the proposed predictive model. The functional forms that describe the temporal evolution of the K‐T model parameters can effectively represent strong non‐stationarities of the ground motion. Fully non‐stationary ground motion time histories can be generated through the powerful Spectral Representation Method. A Californian subset of the available NGA‐West2 database is used to develop and calibrate the predictive model. Samples of the model parameters are obtained by fitting the K‐T model to the database records, and the resulting marginal distributions of the model parameters are efficiently described by standard probability models. The samples are translated to the standard normal space and linear random‐effect regression models are established relating the transformed normal parameters to the commonly used earthquake scenario defining predictors: moment magnitude Mw, closest‐to‐site distance Rrup, and average shear‐wave velocity at a site of interest. The random‐effect terms in the developed regression models can effectively model the correlation among ground motions of the same earthquake event, in parallel to taking into account the location‐dependent effects of each site. For validation purposes, simulated acceleration time histories based on the proposed predictive model are compared with recorded ground motions. In addition, the median and median plus/minus one standard deviation elastic response spectra of synthetic ground motions, pertaining to a variety of different earthquake scenarios, are compared to the associated response spectra computed by the NGA‐West2 ground motion prediction equations and found to be in excellent agreement.

Influence of the Seismic Intensity of the Area on the Assessment of Dynamic Resistance of Bridge Structures

The paper presents the results of the studies assessing the resistance of the existing bridge structures located in areas of varying seismic intensity. The basis for the analysis was an exemplary reinforced concrete road flyover of a slab span structure. Numerical calculations by the Finite Element Method were carried out, using the response spectrum approach in the dynamic analysis, with the use of the standard response spectra according to the Eurocode 1998 and the standard acceleration response spectra for the Upper Silesian Coal Basin and the Legnica-Głogów Copper District. For each individual analyzed case, the structure response to the assigned kinematic excitation was compared with the effects of load combinations adopted at the design stage, setting the limit values of the design horizontal ground acceleration in the horizontal plane (ag,Hmax) and the vertical plane (ag,Vmax). This allowed to assess the effect of seismicity of a specific area on the design dynamic resistance of the studied object. The paper discusses the manner of interpretation and the scope of applicability of the obtained results.

A modified response spectrum analysis procedure to determine nonlinear seismic demands of high‐rise buildings with shear walls

SummaryThe standard response spectrum analysis (RSA) procedure prescribed in various design codes is commonly used by practicing engineers to determine the seismic demands for structural design purpose. In this procedure, the elastic force demands of all significant vibration modes are first combined and then reduced by a response modification factor (R) to get the inelastic design demands. Recent studies, however, have shown that the response of higher vibration modes may experience much lower level of nonlinearity, and therefore, it may not be appropriate to reduce their demand contributions by the same factor. In this study, a modified RSA procedure based on equivalent linearization concept is presented. The underlying assumptions are that the nonlinear seismic demands can be approximately obtained by summing up the individual modal responses and that the responses of each vibration mode can be approximately represented by those of an equivalent linear SDF system. Using 3 high‐rise buildings with reinforced concrete shear walls (20‐, 33‐, and 44‐story high), the accuracy of this procedure is examined. The inelastic demands computed by the nonlinear response history analysis procedure are used as benchmark. The modified RSA procedure is found to provide reasonably accurate demand estimations for all case study buildings.

Possibilities and limitations of innovative retrofitting for masonry churches: Advanced computations on three case studies

The use of fiber reinforced polymers (FRP) represents an interesting option to inhibit the formation of partial collapse mechanisms on macro-blocks, which is a typical failure mode shown by masonry churches under seismic actions. Furthermore, FRP strips exhibit a very good performance at failure, low invasiveness and high speed of execution. This study provides an insight into the possible applications of FRP on three masonry churches damaged by the 2012 Emilia seismic sequence. Several different linear and non-linear analyses are carried out, including standard response spectrum analyses, limit analyses with both pre-assigned failure mechanisms and Finite Elements (FE), pushover and non-linear dynamic analyses. A remarkable consistency is found between the real seismic performance of the churches and the results obtained through both limit and advanced non-linear dynamic analyses. In particular, both the damage distributions and the active failure mechanisms derived from the numerical analyses are consistent with those observed on the churches after the seismic event. A seismic upgrading of the churches through the application of FRP is proposed, using a proper design procedure based on comprehensive advanced FE computations, with the aim of obtaining the required seismic performance and limited invasiveness. The interaction between FRP strips and masonry substrate is accounted for assuming the FRP behavior in agreement with Italian Guidelines for strengthening with composite materials (CNR DT200). It is found that through a rational design procedure of the FRP strengthening intervention it is possible to prevent the premature collapse of the macro-elements, considerably increasing their load carrying capacity.

SOCIAL RESPONSIBILITY EFFECT ON CLIENT – ORIENTATION REGARDING TO MEDIATORY ROLE OF JOB SATISFACTION AND REALIZED ORGANIZATIONAL COMMITMENT BY WORKERS

Present research follows to study social responsibility effect on client-orientation regarding to mediatory role of job satisfaction and realized organizational commitment by Guilan Melli bank workers . Present research statistical case is 315 Guilan Melli bank branches workers in iran to collect data and sampling method is classifying random. Using tool is Chronbach alpha for standard stability and response spectrum is 5 points likert. Questionnaire has made in field method and research is descriptive- analytical. To obtain data has used Liserl method. Deductive software has used structural equations modeling and data analysis showed that social responsibility eas effective directly and through job satisfaction and organization commitment on client tendency among workers.

Response Spectra of Ground Motions and Building Foundation Vibrations Excited by Rockbursts in the LGC Region

Surface vibrations induced by mining rockbursts resulting from underground exploitation in the mines in western Poland were analyzed and classified into three different categories. Comparison of the accelerograms simultaneously recorded on the ground and on the foundations of typical buildings, as well as the response spectra determined on the basis of these records, leads to the conclusion that ground vibration characteristics have a significant influence on the nature of vibration transmission from the ground to the building foundation. Analysis of the response spectra, separately determined from both ground vibrations and building foundation vibrations, indicates that the standard response spectrum based on building foundation vibrations is more useful in the design of new buildings in areas of mining tremors than the spectrum based on ground vibrations. Moreover, the usefulness of the models of soil-structure interaction based on seismic data in California was investigated with respect to mine-induced rockbursts in Poland.