Recorded Time Histories Research Articles

Result Comparison of Spectral Matching Between <i>Seismomatch</i> and <i>Specmatch </i>Computer Program

The earthquake ground motion, or acceleration time history, caused by an earthquake event, is an earthquake acceleration wave that can be utilized as a basis to design earthquake-resistant civil engineering buildings. The earthquake acceleration time history is needed as a basis to determine the earthquake loading for the building structure design. A time history can be developed from recorded data using spectral matching software. In this process, the response spectra of the recorded time history are matched to a specific target spectrum. The target spectrum is developed based on the Indonesian National Standard known as SNI 2012 (SNI code). The response spectra derived from this standard are referred to as the design response spectrum. These response spectra adopted by the SNI code are based on the ASCE code from the US. Two spectral matching software programs, namely Seismomatch and Specmatch, are employed for this purpose. In this study, both of software programs are utilized to match the response spectra of a time history to a predefined response spectrum. The results of the matching process indicate that Seismomatch does not produce a satisfactory match between the response spectra of the time history and the target spectrum, whereas Specmatch provides a matching result where the response spectra of the time history nearly perfectly align with the target spectrum.

Effects of aftershocks on the performance of steel building frames

Damages done by the earthquake excitation have attracted a significant amount of attention on aftershock effects on building structures. Seismic design of buildings is done without paying much attention to the repeated sequence of mainshock-aftershock events. It has been found that a structure may sustain the mainshock but is damaged during the aftershock. In this paper, the performance of steel building frames is evaluated with respect to the aftershocks followed by the mainshock. For this purpose, 4-, 8- and 12-story steel building frames are considered and are subject to synthesized earthquake, response spectrum compatible mainshock-aftershock sequences. For making the sequences, Bath’s law is applied. A nonlinear time history analysis is performed for a variety of synthesized sequences of the mainshock and aftershocks. The variation is implemented by selecting any single mainshock out of an ensemble of 8 mainshocks. In the sequence, a maximum of seven aftershocks followed by a mainshock is used. Time history record used for the analysis is developed by joining the synthesised earthquakes in series keeping a gap of of the 40 s between two events. The performance parameters used in the study are maximum inter-story drift ratio during an event (MIDR), residual inter-story drift ratio after the event (RIDR), maximum residual top story displacement and spread of hinges. The performances of the three building frames are compared in the study. It is seen that the 12-story frame is damaged to collapse level after 3 aftershocks, while the 4- and 8-story building frames survive seven aftershocks.

Carbon Storage Tanker Lifetime Assessment.

CO2 capture and storage (CCS) is an important strategy to reduce global CO2 emissions. This work presents both cutting-edge carbon storage tanker design, as well as novel reliability method making possible to extract useful information about the lifespan distribution of carbon capture systems from their recorded time history. The method outlined may be applied on more complex sustainable systems that are exposed to environmental stresses throughout the whole period of their planned service life. The latter is of paramount importance at the design stage for complex engineering systems. Novel design for CCS system is discussed and accurate numerical simulation results are used to apply suggested novel reliability methodology. Furthermore, traditional reliability approaches that deal with complex energy systems are not well suited for handling high dimensionality and cross-correlation between various system components of innovative dynamic CO2 storage subsea shuttle tanker. This study has two distinctive key features: the state of art CCS design concept, and the novel general purpose reliability method, recently developed by authors, and particularly suitable for operational safety study of complex energy systems.

Validation metrics and turbulence frequency limits for LES-based wind load evaluation for low-rise buildings

The accuracy of Large-Eddy-Simulation (LES) in modeling wind loads, especially components and cladding loads, does not currently fulfill its potential. The lack of extensive consideration for wind loading requirements and their direct influence on LES duration and mesh size are identified as research gaps. This study presents a validation metric for LES modeling of low-rise buildings, including the wind field and aerodynamics. Most of the proposed validation requirements are adapted from Boundary Layer Wind Tunnel (BLWT) testing requirements to highlight the challenges and opportunities for LES. The turbulence spectral frequency limits significantly contribute to the cost-accuracy trade-off in LES. A stationarity test of recorded time histories is proposed to determine the optimal duration, i.e., low-frequency limit, for statistical parameters other than the peak. An analytical expression is proposed for the LES mesh size estimation from the target maximum frequency limit and corresponding spectral energies. The proposed validation metric is demonstrated with LES models of a low-rise building targeting respective BLWT tests in three wind directions and in three exposures. Despite some limitations, the peak Cp error was within ±10% of the BLWT value range. The optimal normalized durations from LES were one order of magnitude shorter than those from the BLWT cases. The peak values did not show a significant difference in trend from BLWT; hence the duration dependence of peak uncertainties remains relevant for LES. The BLWT data supports the previously proposed high-frequency limit of two. LES models can produce reasonably acceptable wind loads with proper attention to the existing and new requirements, as shown in the present study.

Experimental assessment of proposed seismic strengthening scheme for adobe structures

A new scheme of seismic strengthening of adobe structures has been proposed in this paper. The scheme involves horizontal and vertical bands of steel wire mesh plastered with cement-sand mortar. The effectiveness of the proposed scheme is assessed by dynamically testing a half-scale model of the adobe structure on a shaking table. The acceleration time history record of the 1995 Kobe earthquake was used to simulate the ground motion for the strengthened model which was increased sequentially in increments of 25% of peak ground acceleration (PGA). Initial (hairline) cracks were observed in the in-plane wall of the model at a PGA of 0.439 g. Although the out-of-plane walls also sustained damages, the in-plane walls were the most damaged parts of the structure. The proposed strengthening method reduced the torsional irregularity of the structure. It also increased strength, ductility and energy dissipation capacities of the walls. The data of observed structural damages and building drift were used to propose four performance levels for the strengthened adobe structures corresponding to the applied PGAs of ground motion.

Seismic performance of RC-ECC composite frame by eliminating shear reinforcement in beam-column joint: Shake table tests

The inherent vulnerability of beam-column joints to seismic loading and steel congestion are two major research problems connected with beam-column joints of moment-resisting frames. The experimental study presented herein addresses these research questions and seeks to solve them by using Polyvinyl Alcohol based Engineered Cementitious Composite (PVA-ECC) in beam-column joints without transverse shear reinforcement. The study included the manufacture and shake table testing of two 1:3 reduced scale one bay two-story moment-resisting frame models using simulated earthquake motions. To evaluate the performance of ECC beam-column joints without shear reinforcement, two frame models, one with and the other without shear reinforcement in the beam-column joints, were prepared and tested. The acceleration time history record of the 1994 Northridge Earthquake USA was used for the excitation of specimens at different levels to produce progressive damage up to the near collapse state. The observed damage mechanism of tested models was recorded, and the response parameters, including floor displacement and acceleration, were measured. The measured data was processed to develop a lateral force-displacement envelope curve for the supposed prototype frames and calculate their seismic design factors (ductility, overstrength, and response modification). Comparison of the seismic performance parameters of the two prototype frames reveal that the ECC beam/column joint without shear ties performed marginally inferior to the ECC beam-column joints having shear ties but it still achieved a 75% larger R-factor compared with the code specified value.

Study on seismic performance of reinforced concrete multi-storey building considering soil-structure interaction effect

The dynamic interaction between structure, foundation, and soil, known as 'soil-structure interaction', determines the seismic response of high-rise buildings susceptible to failure owing to earthquake loads (SSI). Research on SSI in typical reinforced concrete (RC) buildings is very restricted, especially when it comes to combining structural and geotechnical fields of competence. The available code regulations are reviewed to ensure a sufficient design to withstand seismic loads. In this study, Abaqus (Simulia's Abaqus 6.19) software was used to conduct a series of three-dimensional finite element analyses to investigate the effects of high-rise structures' number of stories (20, 25, and 30 stories) on seismic performance as well as the size of raft foundation with SSI effects. The seismic loading input was computed using the El-Centro acceleration time-history record for fixed-base RC buildings and the dual framed-shear wall system fixed to the foundation and soil field. The effects of the height of RC building models, foundation size, and soil type on lateral storey displacement, inter-story drift, natural period, and shear pressures are explored. According to the findings, the number of stories and SSI significantly impact the structural loading of RC high-rise buildings.

Validation of displacement-based procedures for rocking assessment of cantilever masonry elements

The seismic assessment of cantilever elements in masonry structures is a relevant topic because of their high vulnerability and since they often involve artistic assets (such as bell-gables, parapets or pinnacles). Due to the complexity of nonlinear dynamics of cantilever systems, displacement-based assessment (DBA) procedures have been developed with the main advantage to be less demanding and, therefore, engineering practice-oriented. Various international codes already adopt these procedures but with different choices in their implementation, e.g. in the idealisation of the single degree of freedom or the method to assess the seismic displacement demand. However, despite their widespread use, a systematic validation and comparison among them is not available yet. The aim of this paper is to assess the reliability of five DBA methods available in literature and codes. To this aim, three cantilever elements with a different slenderness were analysed, both considered as laying on the ground floor or atop a supporting structure. Then, incremental dynamic analyses (IDA) have been performed by using several recorded time histories and the results were considered as the reference solution to be compared with the ones obtained by applying the examined DBA procedures. In particular, the results were processed in terms of the peak ground acceleration (PGA) alternatively leading to the attainment of the ultimate limit condition assumed by the codes or to the block overturning. The IDA clearly highlighted that the displacement demand is very sensitive to the intrinsic features of each record. The comparison in terms of fragility curves allowed evaluating robustness, reliability and safety margins of the static displacement-based previsions. Despite the complexity of the problem, the results showed that, as long as proper definitions of the ultimate displacement capacity and proper assumptions for evaluating the seismic displacement demand are adopted, the DBA approach provides safe and reliable estimates.

Seismic performance of fuel assemblies and impact force correlations with intensity-compatible sets of recorded ground motion time histories

In the present paper, the seismic performance of fuel assembly rows is analyzed for historical ground motion records of seismic events in Europe that are compatible with the seismic hazard background of Goesgen NPP, at the frequency of exceedance of 10-4/a. The benefit of the analysis is twofold. Firstly, it represents an alternative approach to standard fragility analysis, which is based on ground motions matching the UHS. Instead, the present analysis is based on recorded time histories which can be viewed as an actual earthquake scenario at the site.Secondly, the analysis looks at ground motion intensity measures other than the peak ground acceleration, which are considered to be equally or even more relevant for actual damage. Ultimately, these results can lead to more realistic fragility estimates – and hence risk footprint in the PSA – of the FA.

The statistical properties of raw knock signal time histories

Traditional processing of knock signals reduces each recorded time history to a single scalar knock intensity metric for each engine firing, thereby losing all information relating to the phasing and evolution of knock over the combustion period. In this work, a statistical analysis of raw knock cylinder pressure and accelerometer signal time histories has been performed showing how the nonstationary stochastic characteristics of these signals evolve as a function of crank angle, and as a function of spark timing. The data are shown to closely approximate a cyclically independent process whose 2-dimensional covariance function captures both the non-stationary deterministic processes taking place within a cycle as well as the stationary random variations from one cycle to the next. A (time-varying) dual-Gaussian model for the distribution of these cyclic variations was fitted to the data, thereby enabling them to be characterized as the sum of knocking and non-knocking populations. The parameters of the model, which describe these populations separately, provide further empirical insight into the knock process.

Response spectrum analysis of a G+4 building with mass irregularity on a sloped surface

The behaviour and stability of a multi-storey building in a sloped region depends on structural configuration. Irregularities in the structure are recognized as one of the chief sources of its failure. Structures commonly have a grouping of irregularities such as vertical irregularity, mass regularity, stiffness irregularity etc. Also, for the analysis of such a structure, it is necessary to carry out dynamic analysis to determine the maximum peak response of the building with respect to the natural time period. Since it would be difficult to get the time history record for all the places, it is feasible to go with Response Spectrum Analysis. In this paper, a G+4 RCC building having each storey of height 3.5m placed in the sloping ground with horizontal angle of inclination 20° for the purpose of dwelling of people during disaster with one of the storey to be used for storage of food and water which induces Mass irregularity. The structure is modelled in ETABS software. Here the mass irregularity is induced at every storey by inducing on one storey at a time for 3 different zones (III, IV, V) and the same has been analysed by inducing gravity loads and seismic load cases using Response Spectrum Analysis. The response of the structure with respect to variation in the Storey Drift and Storey displacement has been recorded and will be discussed elaborately.

Study the seismic response of reinforced concrete high-rise building with dual framed-shear wall system considering the effect of soil structure interaction

Abstract During strong earthquakes, civil structures are subjected to damaging forces. Tall buildings if damaged would threaten the life safety of inhabitants or at least would cease to offer the same level of functions. For this reason, tall buildings should be designed in accordance with the seismic provisions that ensure suitable performance during and aftermath. One of the factors that dominate tall buildings’ design is the dynamic soil-structure interaction (SSI) that differs significantly with the variation of several aspects. Soil type that incorporate the building’s foundations, the height of the building, the type of lateral load resisting system, and many other factors. In this research authors have considered SSI using the direct method (i.e. FEM soil medium) and studied the effect of changing soil type (soft soils and hard soils) on the performance of the tall building under consideration. The building was taken to be 16 stories, wall-framed dual system for seismic loading resistance. Semi-infinite elements from Abaqus (simulia’sAbaqus 6.14) solid element library were used to model the boundaries of soil media. The seismic loading input was El-Centro acceleration time-history record. Results of analysis showed differences between soft soil and hard soil types, especially on the displacements and base shear values.

Time History Analysis of Frame Structure Systems by State-space Representation Method

This paper develops the state-space representation (SSR) in the field of seismic analysis of the building structures. Dynamic analysis of multi-degree-of-freedom structures involves the solution of second-order linear differential equations which they represent the equation of motion of the structure. In this paper, a SSR was formulated to replace differential equation with two coupled first-order linear differential equations. The objectives of this study are as follows: (i) To implement the SSR as a powerful tool in dynamic analysis of frame structures and (ii) to conduct a linear time history analysis for large structures subjected to ground acceleration and the seismic responses of the building were studied as well. The analysis was based on the assumption that the system is elastic linear time-invariant system and material nonlinearity is not considered. The 1940 El-Centro earthquake time history record has been used in the study. There are many effective traditional methods which can be used for carrying out linear dynamic analysis of the structures, however, this paper introduces a state-space model as an alternative approach to perform this analysis. The advantage of this method, it works properly with MATLAB software, gives explicit result for time-invariant systems, applied to multi-input and multi-output control systems, solve the equation of motion for complicated dynamic problems.

Analisis Perilaku Struktur Beton dan Baja Dengan Metode Levelling Time History (Studi Kasus Gedung ITERA, Lampung, Indonesia)

The selection of structural material types can be based on analyzing the behavioral of the structure by giving a nonlinear dynamic earthquake load of time history. Because in Indonesia doesn’t have any data of time history record, it is necessary to match the time history data with the design spectrum response. Gedung E ITERA is modeled on reinforced concrete structures and steel structures with open frame models for the same as built drawing. Then can be evaluated the structural behavior that is like mass participation, plastic design, displacement, rotation, and base shear with time history load that will be levelling (levelling time history). With levelling the time history load , it can be found the first structural part that collapses and the maximum load that can be retained by the structure for one of the mitigation effort. The analysis uses a nonlinear dynamic time history analysis with the most dominant combination is earthquake combination. The results of this study show the differences in structural performance, the location of structural failure, and the maximum load that can be retained by the reinforced concrete structure and steel structure of gedung E Itera.

Design and development of low-cost HDRBs seismic isolation of structures

This paper presents a simplified procedure for the preliminary seismic design of high damping rubber bearings (HDRBs) for seismic isolation of structures. The procedure is consistent with the ASCE 7-16 specified seismic design for isolated structure, and starts defining the seismic base shear coefficient (CS) demand for superstructure, reduced by an appropriate response modification factor (RI) for isolated structure. The target time period for isolated structure is identified from the (CS/RI) versus time period plot, corresponding the available base shear capacity of structure. The required lateral shear stiffness of HDRBs is calculated, assuming a reasonable height-to-length ratio of bearing. The preliminary design suggests the required dimensions (height, width and length) of bearing, required thickness of elastomers and number of steel shim plates. The proposed procedure was validated for the seismic isolation of three-story deficient RC frame structure, located in a high seismic zone with a design basis PGA of 0.44 g. Representative reduced scale bearings were locally produced and tested on shake table, using an acceleration time history record of 1994 Northridge earthquake, through multi-levels excitations ranging from 0.10 to 1.0 g. The hysteretic and shear force–deformation response curves were analysed to develop constitutive relationship and hysteretic model for HDRBs. The derived hysteretic model parameters were incorporated in SeismoStruct, using plastic and bi-linear hysteretic models, for testing and validation against the shake table tests. The numerically predicted to experimentally observed peak displacements/forces exhibited a little over-prediction using bi-linear hysteretic model while a little under-prediction using plastic hysteretic model. Combining results from both the hysteretic models, and averaging, minimized the average error to less than 0.10%. Comparative seismic analysis of both as-built and isolated frames was carried out for both design basis earthquakes DBE and maximum considered earthquake MCE (considered as 3/2 of DBE), showing promising behaviour of the simplified design procedure and locally produced HDRBs.

Solution and validation of a three dimensional tropical cyclone boundary layer wind field model

A tropical cyclone (TC) wind field model is essential for assessing its hazard. The presented study investigates the characteristics of the wind field predicted by a nonlinear TC wind field model which is based on the momentum equation and continuity equation. The model considers the nonlinear friction force near the surface and height varying eddy viscosity that is related to the turbulence kinetic energy. The solution procedure is based on the finite difference method and using an implicit solution algorithm. Numerical analysis carried out indicates that the use of the implicit algorithm is very efficient, and numerical dissipation is negligible. The solution to the wind field indicates that the predicted vertical wind profile matches well that derived from dropsonde data. Comparison with the results from other TC wind field models indicates that the vertical wind speed predicted by the considered model is consistent with that of a sophisticated weather prediction model. The adequacy of the considered model is further validated through comparison of model prediction and recorded time history of wind speed at surface stations for several historical TC events.

Retrieving the constitutive properties of a concrete target from a single instrumented penetration test

Penetration into concrete is an important problem that attracted many researches who developed analytical models and numerical solutions. Most of the advanced methods account for the material properties through their constitutive equations, combined from the failure envelope and the equation of state. These properties are rarely available in many cases, and in different experimental reports it is missing. For lack of any other option, analysts borrow available equations that were developed for other concrete types, with the doubt of their suitability. In a limited number of tests, instrumented projectiles are used and the deceleration time history is recorded. Rarely, the constitutive properties are also provided and analysis can be conducted. Otherwise, analysis cannot be carried out and prediction and validation of the recorded deceleration curve cannot be conducted. The present article refers to such instrumented tests where the constitutive properties are not available. It aims at unveiling the relationship between the deceleration curve and the constitutive properties and at solving, for the first time, the inverse problem of a penetration problem in order to retrieve major constitutive equation parameters from the acceleration time-history record. The major new feature of the present article is identification of the failure envelope parameters in the Mohr–Coulomb form as well as the parameters of the Shock Hugoniot equation of state for which procedures have been developed. The present approach allows to retrieve required information regarding the equation of state and failure envelope from a single instrumented experiment that provides the projectile deceleration time-history record. It is shown that the retrieved parameters of the failure envelope and the equation of state are in good agreement with reported constitutive parameters that are based on experimental data. The retrieved data allow to carry out penetration time-history predictions of different projectiles at different impact velocities on the same concrete.

Experimental metrics for detection of detailed balance violation.

We report on the measurement of detailed balance violation in a coupled, noise-driven linear electronic circuit consisting of two nominally identical RC elements that are coupled via a variable capacitance. The state variables are the time-dependent voltages across each of the two primary capacitors, and the system is driven by independent noise sources in series with each of the resistances. From the recorded time histories of these two voltages, we quantify violations of detailed balance by three methods: (1) explicit construction of the probability current density, (2) constructing the time-dependent stochastic area, and (3) constructing statistical fluctuation loops. In comparing the three methods, we find that the stochastic area is relatively simple to implement and computationally inexpensive and provides a highly sensitive means for detecting violations of detailed balance.

Structure Behavior Analysis with TIME History Levelling Method (Case Study in Building E ITERA)

Mitigation of structural failure can be based on analyzing the behavioral of the structure by giving a nonlinear dynamic earthquake load of time history. Because Indonesia doesn’t have any data of time history record, it is necessary to match the time history data with the design spectrum response. Gedung E Itera is modeled on reinforced concrete structures with open frame models like as built drawing. Then can be evaluated the structural behavior that is like mass participation, plastic design, displacement, rotation, and base shear with time history load that will be levelling (levelling time history). With levelling the time history load , it can be found the first structural part that collapses and the maximum load that can be retained by the structure for one of the mitigation effort. The analysis uses a nonlinear dynamic time history analysis with the most dominant combination is earthquake combination. The results of this study show structural performance, the location of structural failure, and the maximum load that can be retained by the reinforced concrete structure of gedung E Itera.

Dynamic Testing of Seismic Resistant Cob Structure for Post-Earthquake Reconstruction

ABSTRACT This paper presents the details of shaking table tests on a seismic-resistant cob structure. The seismic resistance of the model was increased using bamboo strips and steel wire mesh. A one-third scale model of a prototype cob building was used to observe its dynamic performance using a shaking table. The model was subjected to different levels of acceleration time history record of the 1940 El Centro earthquake. These levels were varied from 25% (R25) to 200% (R200) in increment of 25%. The data of acceleration of both the in-plane and out-of-plane loaded walls and displacement of the model were recorded. The damage to the model began with the appearance of cracks in the in-plane loaded wall at R100 level of dynamic excitation that changed the structure’s dynamic characteristics. The size and numbers of cracks increased in the walls of the model with increased levels of peak ground acceleration (PGA) and the structure became heavily damaged at R200 level of test run. The acceleration response and its amplification were higher for the in-plane loaded wall as compared to the out-of-plane loaded wall. The maximum acceleration for the in-plane and out-of-plane loaded walls was recorded as 0.65 g and 0.57 g, respectively, in the prototype domain. The torsion effects caused unequal structure displacement at its east and west ends at roof level. The energy dissipation of the wall continued until the end of testing. The observed structural damages corresponded to four performance levels that were correlated with the damage limit states.