Linear Time History Analysis Research Articles

Analysis of Reinforced Concrete Structure Subjected to Blast Load

The research focuses on a specific standoff distance of 15m & 20m , a critical parameter in blast analysis, to gain a understanding of the building's behavior under static loading conditions of blast load weight of 150kgs & 100kgs of TNT. To simulate realistic scenarios, the models are subjected to appropriate boundary conditions, including foundation constraints to account for the building's interaction with the ground. The blast load is assigned as joint loads, considering the standoff distance of the blast from the source. The standoff distance significantly influences the building's response to the blast, with profound implications for structural integrity and security. The Analysis of the Bare frame with blast load added as Joint Load, the deflection is controlled by adding Shear walls along various location along the periphery & core for 10 Story RCC Structures. The analysis is conducted using linear time history analysis (Response Spectrum Analysis) within ETABS, capturing the response of the building. Roof Displacement, Base Shear, Story Drift, Stiffness, Time period & Modal participation mass ratios are monitored during the analysis. The outcomes of this study contribute valuable insights into the structural responses of buildings to blast loads at specific standoff distances. This research advances our understanding of blast effects on buildings thereby enhancing the security and resilience of vital infrastructure in the face of evolving threats. Keywords: Blast Load, Response Spectrum Method, Roof Displacement, Base Shear, Story Drift, Stiffness, Time period & Modal participation mass ratios.

Seismic Performance Evaluation of Irregular Auditorium Building based on ASCE 41-23

This study discusses the seismic performance evaluation of an irregular auditorium building. The building is an educational facility which has roof span up to 46 meters, column height up to 10 meters, beam span up to 15 meters, cantilever up to 6.50 meters, 2 inclined columns with the angle up to 54.72°, and 1 transfer column with 1 transfer beam. The evaluation process was carried out using Tier 3 method with linear dynamic procedure which consisted of Response Spectrum Analysis (RSA) and Linear Time History Analysis (LTHA) according to ASCE 41-23 using SAP2000 subjected to short (S s ) and long (S ) period of earthquakes. The building is designed to Risk Category IV, which the target performance levels for structural components are Immediate Occupancy (IO) for Basic Safety Earthquake 1 for New Building (BSE-1N) and Life Safety (LS) for Basic Safety Earthquake 2 for New Building (BSE-2N). Even though the building had a torsional strength irregularity, the percentage of components with a Demand-Capacity Ratio value that did not meet the requirements was 9.87% of the total components; hence the linear procedure was assumed to be still applicable. Analyses showed that the average acceptance criteria ratio of the components with the RSA method was lower than with the LTHA method but the percentage of the components with acceptance criteria ratio exceeding 1 using RSA method was higher than using the LTHA method. In addition, the results indicated that the average performance level of the components was IO for BSE-1N and LS for BSE-2N, which both results had met the expected performance level targets. However, the maximum performance level of the components did not meet the IO performance level target for BSE-1N and did not meet the LS performance level target for BSE-2N.

Shaking table test of a full-scale lightweight bolt-connected concrete sandwich wall panel structure: Overview and seismic analyses

This study proposed a novel lightweight bolt-connected concrete sandwich wall panel structure with the advantages of thermal insulation, construction efficiency, demountability and remountability. The seismic design of the structure was employed a non-equivalent cast-in-place method, resulting in appropriate configurations of horizontal and vertical bolted joints. Subsequently, a shaking table test was carried out to investigate the damage pattern, dynamic characteristics and dynamic responses of a full-scale structure. The test results demonstrated that the overall damage was moderate, which exerted a few impacts on the structural capacity or integrity. The global responses, including small displacement response, minor torsion response, and high energy dissipation capacity were found, as well as local responses, such as small strains in the steel plates and a slight loss of bolt prestress. The maximum inter-story drift ratio was below the elastoplastic inter-story drift ratio limit θu = 1/120 defined in Chinese code GB 50011. In general, the structure presented high lateral stiffness and sufficient capacity against high-intensity ground motions. A numerical model was developed, wherein precast components were established by multi-layer shell elements and bolted joints were simulated by 3-DoF nonlinear springs. Linear modal and nonlinear time history analyses were performed and compared with the experimental results. The simulation results showed good agreement with the experimental ones, confirming the ability of the model to capture global responses.

Optimizing Seismic Design of Multi-Tower Buildings Using Sky Bridge Isolation and BIM: A Case Study

This research aims to extend prior knowledge of sky bridge isolations in a design case study that complies with building codes, focusing on the design of a multi-tower building linked with a sky bridge and its isolation system. Building Information Modeling (BIM) is used during the design process. Linear time history analysis is performed to capture seismic responses without statistical distortion of response combinations. Link elements are used to simulate the isolations, and the ground motions are excited in bidirectional directions. The experimental results demonstrate that using an isolation system at the sky bridge connection improves torsional behavior, as evidenced by a 12% reduction in torsional mass contribution in the fundamental mode shape of the buildings. Other notable improvements include better lateral force distributions and optimization of reinforcement volume by 36.91% at maximum. Additionally, convenient post-design procedures, such as automated design visualizations and quantity surveys of reinforcements are reported through using BIM.

Study on Ground Motion Amplification in Upper Arch Bridge Due to “W”-Type Deep Canyon Using Boundary-Integral and Peak Frequency Shift Methods

The study of the dynamic response characteristics of “W”-type deep canyon terrain to double-span concrete arch bridges under earthquake action holds great practical significance. In this research, a bridge in Sichuan Province is taken as the object of study. The boundary-integral equation method and peak frequency shift method are combined to apply an embedded linear time–history analysis algorithm to the finite element spatial dynamic calculation model of the entire bridge, resulting in an improved model. By comparing these two methods with model test results, the seismic response characteristics of the middle part of a “W” concrete arch bridge under different foundation depths and seismic intensities are examined. The boundary integral equation method was utilized to calculate ground motion response at any point on site, revealing a significant amplifying effect of increased seismic wave intensity on acceleration response at the top of the arch bridge. When input seismic wave intensity increased from 0.1 g to 0.3 g, maximum acceleration at buried depths of 3 m and 8 m in the middle of the arch bridge foundation increased by 102.63% and 79.16%, respectively, indicating that shallow buried depth structures are more sensitive to seismic wave intensity. Furthermore, using peak frequency shift rules for analyzing seismic wave propagation characteristics in “W”-type deep canyon topography confirms the sensitivity of shallow buried depth structures to seismic wave intensity and reveals the mechanism through which topography influences seismic wave propagation. This study provides a helpful method for understanding the propagation law and energy distribution characteristics of seismic waves in complex terrain. It was observed that the displacement at the top of the arch bridge increased significantly with an increase in seismic intensity. When subjected to 0.1 g, 0.2 g, and 0.3 g EI-Centro seismic waves, the maximum displacement at the top of the arch bridge model with a foundation buried depth of 3 m was 8 mm, 32 mm, and 142 mm, respectively. For arch bridge models with an 8-m foundation buried depth, these displacements were measured at 6.2 mm, 21 mm, and 68 mm, respectively. The results from model tests verified that increasing the depth of foundation burial effectively reduces the displacement at the top of the structure. Furthermore, by combining a boundary-integral equation method and peak-frequency shift method, this study accurately predicted significant influences on W-shaped double deep canyon topography from seismic response, and successfully captured stress concentration and seismic wave amplification/focusing effects on arch foot structures. The calculated results from both methods align well with model test data which confirm their effectiveness and complementarity when analyzing seismic responses under complex terrain conditions for bridge structures.

Seismic Fragility Analysis of Existing Old Newari Brick Masonry Building in Pokhara Valley

Most of the building stock in Nepal is based on masonry construction, which includes monumental, administrative, and residential structures. These structures are vulnerable during earthquakes, as evidenced by the massive structural damage, loss of human life, and property damage due to a lack of proper assessment and appropriate strengthening measures. An analysis of the seismic vulnerability of existing old Newari brick masonry buildings in the Pokhara Valley is presented. These buildings were built using indigenous knowledge and technology. The investigation is based on analytical studies, with some material properties obtained from field tests. Proper modeling of a masonry structure is crucial for reliable seismic resistance and structural design. However, modeling a real masonry structure is a challenging and computationally demanding task due to its complicated framework, requiring in-depth knowledge, realistic material properties, and relevant information. The aim of this research is to assess the seismic performance of old Newari masonry buildings using stress level and fragility curves. The research issues are addressed analytically through linear time history analysis using the finite element program-based software Sap 2000 v20. In dynamic analysis, numerical building models were subjected to three synthetic earthquakes. The performance status of the building based on various stress levels is evaluated, and weak regions are identified. The fragility curve of the structure is assessed, considering the ground motion parameters in the locality. The fragility function is plotted with the probability of failure at an interval of 0.10 g. The results of the analysis highlight that the studied structure is vulnerable compared to the codal provisions and standard recommendations.

Modification of wavelet-based downsampling method to reduce computational error in nonlinear dynamic analysis

One of the significant obstacles in conducting linear and non-linear time history analysis is its time-consuming nature. In this article, a new downsamlping method based on discrete wavelet transform (DWT) and smoothing is proposed to overcome this problem. In order to assess the precision of this approach, 50,000 linear and non-linear dynamic analyses of single degree of freedom (SDOF) systems and 300 nonlinear dynamic analyses of frame structures have been performed. One hundred Fema440 records were utilized to generate approximate waves up to the third level and the outcomes of this method were then contrasted with those of DWT. It has been demonstrated that the third-level approximate wave produced by DWT, previously considered dependable in other research, generates significant errors in results and the average error (absolute error percentage of the acceleration spectrum) of its third-level approximate wave is approximately 17.5%. On the other hand, the proposed method generated approximate waves with an average error of less than 4.5% across all behavior coefficients and periods and the error rate decreases as the period and behavior coefficient increase. Analysis of steel moment-resisting frames indicated that the lowest error in both methods is achieved for the base shear and across different engineering demand parameters, the average error rate for the proposed method was below 7.5%. Furthermore, caution must be exercised when employing the proposed method for structures with periods shorter than 0.5 s.

The effect of the gravity on the earthquake performance of roller compacted concrete dams

Roller compacted concrete (RCC) is a dry concrete mixture often utilized in the construction of large dams. The interlayer of the RCC dam, which is the weakest plane of the structure, can easily fail under hydraulic shear load, geological impact, earthquake force and environmental impact. In this study linear and performance analyzes were carried out for eight different scenarios for foundation effect, gravity effect and empty and full reservoir situations. In analyses, the earthquake response and performance of the Akçakoca RCC Dam, taking into account the interaction between the dam and the water. The reservoir water behavior is simulated using the Eulerian-Lagrangian coupled (CEL) approach with finite elements modeling. Linear analyses reveal that hydrodynamic pressure leads to increased displacements and principal stresses. The earthquake performance evaluation of the Akçakoca RCC dam indicates that critical concrete damages are expected based on linear time-history analyses conducted for both empty and full reservoir scenarios. Besides, according to this study, gravity effect clearly increases the earthquake performance of the dam.

Sensitivity of human-induced vibrations and comfort analysis to partially rigid STS joints in timber-to-timber composite floors

The study of floors vibration serviceability represents a well-known challenging task and has a critical role in comfort analysis, assessment and optimization of pedestrian systems in general. To this aim, several consolidated and/or simplified tools are available in the literature to address the most important aspects. In practice, however, most of assumptions for the analysis and verification are based on the use of rough mechanical models of joints and connections, which have indeed a primary role especially for composite floors. In this paper, the attention is given to timber-to-timber floors with inclined self-tapping screws (STS). A parametric Finite-Element (FE) numerical investigation is carried out by taking into account conventional walking features and a case-study timber-to-timber composite beam, well representative of a one-way wooden floor. A major advantage for structural and pedestrian modelling stages is taken from previous literature efforts, while large attention is spent for structural analysis and vibration serviceability assessment tasks, as a function of the STS mechanical parameters (first of all the secant stiffness). Comparative linear modal and non-linear time history analyses are carried out and addressed towards limit mechanical configurations for STS joints, in terms of vibration frequency considerations, as well as structural response and comfort assessment, based on classical performance indicators. The parametric numerical results are further discussed based on simplified methods provided by selected design standards. A critical analysis of major effects due to partial joint rigidity and floor performance classification is presented, both in terms of expected structural safety and comfort levels for similar systems.

Comparison of Linear and Nonlinear Procedures for the Analysis of the Seismic Performance of Straight Multi-Span RC Bridges

The assessment of the seismic performance of transportation infrastructures is of primary importance for the management of the aftermath of an earthquake. To perform such an assessment, various modeling approaches characterized by different levels of accuracy are available and modern seismic design codes provide recommendations about their use. Non-linear time-history analysis (NLTHA) is acknowledged as the most reliable method, but is difficult to implement and is computationally expensive. This paper aims to investigate the viability of less complex methods, but with low computational cost, for the assessment of straight, multi-span bridges and compare their performance against the results of NLTHA in order to quantify the expected accuracy. The study is developed considering three bridge archetypes with either simply-supported or continuous-deck layouts, representative of typical features of the Italian bridge stock. The bridges are analyzed first through nonlinear dynamic analyses, to define the benchmark solution; then linear dynamic analyses, such as Linear Time-History and Response Spectrum Analysis, nonlinear static analyses, such as MPA (Modal Pushover Analysis), and Equivalent Static Analysis are considered. A comparison among the examined procedures is eventually proposed, highlighting the strengths and weaknesses of each approach.

Optimizing the Integration of Building Information Modelling using Response Spectrum and Linear Time History Analysis. Case Study: Irregular Hangar Structure

The increasing use of technology in the construction industry has introduced the concept of Building Information Modeling (BIM), which is widely utilized to streamline construction activities. BIM enables the exchange of data across various disciplines quickly, as well as facilitates analysis, design, and on-site construction processes. The implementation of BIM will be carried out in the analysis and design processes of structures with irregularities to assess the effectiveness and performance of BIM in modeling and analyzing structures. Considering the burgeoning development of the construction industry in Indonesia, there is a necessity for a laboratory hangar dedicated to conducting structural model tests and construction material examinations. The aim of this study is to compare the response and the volume output between the response spectrum and linear time history analysis of an irregular structure. The case study conducted in this research focuses on the 5-stories Laboratory Hangar in Indonesia. The software used in this study includes Autodesk Revit 2023 for BIM modeling and ETABS V21 for structural analysis. Data and model exchange are performed between both software platforms to evaluate the BIM integration between them.

The Seismic Behavior of Buildings with Flat Slab Systems under Near-Fault Ground Motions

It is well known that structural displacement or ductility demands of structures subjected to near-fault ground motions are generally greater than ordinary ground motions. Therefore, the effect of earthquake records in the near region on the seismic behavior of structures has been widely studied in the last decades. Peak ground acceleration (PGA) is an important key parameter, which determines structural behavior. However, structural behavior depends on the distance of the structure to the fault zone, the ratio of peak ground velocity (PGV) to peak ground acceleration, the velocity pulse duration of ground motion, and the natural period of the structure. In this study, the seismic behavior of buildings with flat slab systems was investigated under near-fault ground motions. Linear time history analysis was performed for a 30-storey building designed according to TBEC-2018 using SAP 2000 finite element analysis software. Results were compared with the behavior of the building with a solid slab system. It is concluded that the ratio of PGV/PGA is very effective on the flat slab systems.

Seismic Behavior of an Inter-story Hinged Lateral Resistance Braced Frame

Based on the deflection behavior of structural components occurring at the lateral deformation of moment frames, a new lateral force-resisting system, the R-BRACE Frame (RBF) system, was proposed. This system is capable of effectively limiting the inter-story drift response of tall buildings. An evaluation was conducted using the finite element method program SAP2000 to simulate the internal force distribution and deformation of the system. The equivalent lateral force procedure (ELFP), the capacity spectrum method (CSM), a linear time-history analysis and the pushover method were applied to assess the yielding mechanism of the structure under different earthquake intensity levels. The findings revealed that the sub-unit, referred to as an R-BRACE, had a major impact on improving a structure's lateral stiffness. The placement of R-BRACE units could guarantee controllable stiffness degradation and enhanced seismic ductility, but would not alter the vertical load transfer path of the initial structure, which makes the RBF system an ideal option for seismic retrofitting. KEYWORDS: Lateral force-resisting system, R-BRACE frame, Enhanced lateral stiffness resistance, Seismic ductility

Seismic Control of a Concrete Bridge with Hybrid Passive Control Devices

Abstract: This study focuses on the seismic response of a three-span deck slab RCC T-Girder bridge with and without LRB (Lead Rubber Bearing) and in combination with LRB and FVD (Fluid Viscous Damper). The bridge is subjected to AASHTO, IRC design standards, and IRC Class A vehicle load. Linear time history analysis using CsiBridge and SAPfire is conducted to assess the bridge's seismic behavior. Excessive deck displacement, which can lead to deck failure and bridge closure, is a key concern. The study utilizes finite element analysis with Csibridge and incorporates viscous dampers throughout the bridge. The findings show that the presence of supplemental dampers significantly reduces pier top displacements. Base shear, deck displacement, pier response, and structural time period are the primary response parameters examined. The effectiveness of different isolation system configurations is compared to the non-isolated bridge in terms of these response characteristics. The study offers suggestions for design improvements to enhance the structure's performance.

A Review Paper on Linear and Nonlinear Analysis of G+15 Story Building with and without Shear Wall by using Time History Analysis Method

Abstract: An earthquake is the result of the rapid release of deformation energy stored in the earth's crust, which generates seismic waves. The structures are sensitive to earthquakes and structural damage. In order to take preventive measures against damage to structures due to ground motion, it is important to know the characteristics of ground motion. The most important dynamic characteristics of an earthquake are peak ground acceleration, frequency content, and duration. These characteristics play the main rule in the study of the behavior of structures during earthquake ground motion. Earthquake analysis of a multistory structure is performed using linear and non-linear methods. The response spectrum analysis method is linear dynamic analysis. The time history method is used for nonlinear dynamic analysis. In this paper, the response spectrum method is used for linear analysis. The time history method is used for nonlinear analysis. For the time history method Both analyzes are performed using ETABs software. Linear Time History analysis of RCC building considering 4 different time histories is carried out. The time history data of Bhuj earthquake, Chamba earthquake, Chamoli earthquake and NE (Myanmar) earthquake has been considered. Here, a building has been modelled using Etabs software for seismic analysis and time history analysis. This paper highlights the effects of different time histories of different region on the same structure. The effects under considerations are story shear, building deflection and story drif

Comparative study of sinus earthquake forces and ground motion on structure behavioral response using linear time history analysis method

This study aimed to calculate the design earthquake with a harmonic sine wave approach at a frequency of 1.5 Hz; 2.5 Hz; 3.5 Hz; 4;5 Hz, as well as Loma Prieta, Northridge, and Kobe ground motion. In addition, a structural response review was also carried out based on a comparison of the effects of the ground motion and sine wave earthquake forces. This study used an experimental method of modelling an apartment building with a scale of 1: 50. The case study was located in Mantrijeron, Yogyakarta, which has a seismic category in the medium-size class. The analysis phase began with material definition, element dimension estimation, modelling by analysis software, loading estimation, structural analysis, and comparison of structural responses based on the deviation. The results indicate that the building model could withstand dynamic loads from harmonic waves up to a frequency of 5.5 Hz for one minute of vibration. The most significant deviation is shown at a frequency of 4.5 Hz with an x-axis direction of 0.110 and a y-direction of 0.160. The structural response resulting from ground motion loading shows that the highest deviation occurred due to the influence of the Kobe earthquake, with a deviation of 0.063 in the x-axis direction and 0.054 in the y-axis direction. Based on these results, the effect of harmonic sine waves is greater than the ground motion loading on the response of the building structure, so it is used as an experimental loading through a vibrating table with the actual residual deviation results showing a value of 0.9 mm in the y-axis direction. The difference in structural response results could be caused by the supports and connections modelling in planning through analysis software which could not precisely represent the actual implementation of the building model.

Evaluation of Seismic Response of Irregular Buildings: A Review

The modern design and construction of buildings have led to the adoption of irregular shapes buildings which can attract large seismic forces and induce stress concentrations in the building itself. To investigate this fact a large number of research studies have been carried out. This study presents a review summary of seismic performance of irregular buildings considering vertical irregularity subjected to earthquake loadings. The seismic performance can be found by using linear and nonlinear time history analysis. Different types of irregular buildings are analyzed to review the seismic performance of the structure. It was found that the buildings with the soft story having variation in the storey stiffness yield large inter-storey drift values showing more damage as compared to types of building irregularities.

NSE seismic demand characterization: the case of a Spanish RC residential building

In reinforced concrete buildings, non-structural elements (NSE), such as masonry infills and parapets, constitute the cause of a considerable number of fatalities and huge economic losses in developed countries, in the case of medium magnitude earthquakes (4-6 Mw). As an example, during the 5.2Mw 2011 Lorca (Spain) earthquake, falling debris from unreinforced masonry NSE gave rise to the nine fatalities incurred. The majority of these elements were located in 4 to 6-storey reinforced concrete residential buildings. Within this framework, this contribution addresses the characterization of the seismic demand of NSE through the study of the response of a building in Lorca pertaining to the described structural type, by means of the Floor Response Spectra (FRS) method. For this purpose, the infilled frame model was created in SAP2000 with masonry infills simulated by equivalent struts. The infilled frame model is calibrated so as to fit with the main elastic period of the building, identified by means of ambient vibration tests conducted with a Tromino device. The FRS results obtained with the numerical model by a Linear Time-History (THA) analysis simulating the Lorca earthquake, are compared with the results suggested by the Eurocode in force and by the Italian Building Code. Specifically, in the case of the Italian Building Code, both the simplified formulation for moment resisting frame buildings and the modal superposition spectrum-to-spectrum approaches are considered. Finally, the potential resonance of the dynamic behaviour between the obtained FRS and the natural periods of the masonry parapets located at the top of the building is discussed.

Effect of Soil Type on Dynamic Behavior of Reinforced Concrete Industry Chimneys

Industrial structures built with different materials and methods play an important role in the sector with development of industry and increase in energy need. Many parameters are considered in the design and application phase of industrial structures to provide service for many years. The aim of this study is to examine dynamic behavior of reinforced concrete industrial chimneys depending on soil-structure interaction (SSI). For this reason, a reinforced concrete industrial chimney, which was exposed to the 1999 Kocaeli Earthquake, was chosen as a sample. The effect of soils with different properties (hard, medium and soft) on the dynamic behavior of the selected structure was investigated numerically by linear time history analysis in ANSYS finite element program. The horizontal component of the Kocaeli Earthquake (1999) was used in analyses. As a result of the studies, besides the mode shape and frequency of structure, stress, strain and displacements were also obtained. It has been observed that as the hardness of the soil environment decreases (transition from hard soil to soft soil), chimney apex displacements and stresses on the edge of the voids increase.

Residual displacement ratios of highly damped SDOF systems by considering soft soil conditions

In this paper, residual displacement ratios, Cr, of highly damped single degree of freedom (SDOF) systems are studied by considering soft soil effects. For this purpose, a large number of ground motions recorded on soft soil deposits are used in the analysis. In order to calculate the residual displacement ratios, linear and nonlinear time history analysis are conducted for 79 SDOF systems with lateral strengths of R = 2, 3, 4, 5, 6, damping ratios of ξ = 0.05, 0.1, 0.2, 0.3, and post-yield stiffness ratios of α = 0, 0.03, 0.1 subjected to 426 pairs of earthquake ground motions recorded on soft soil. Therefore, a large number of data is obtained for Cr by using the results of time history analysis. After investigating the impact of lateral strengths, damping ratios, and post yield stiffness ratios on residual displacement ratios, a simplified new equation is proposed with nonlinear regression analysis. The results show that higher damping ratios cause the residual displacement ratios to reduce. Furthermore, comparison of Cr for soft soil and stiff soil conditions indicates the soil condition influence on Cr.