Seismic Performance Of Buildings Research Articles

PUSHOVER ANALYSIS OF EARTHQUAKE RESISTANCE RCC STRUCTURE USING STAAD.PRO SOFTWARE

RCC structure has become crucial to the construction industry in recent decades. A structure must be designed with strong seismic performance in mind. A multi-story reinforced concrete building's seismic performance is planned in compliance with the current Indian code (IS 456 -2000). The study of each structural members performance is conducted using nonlinear static analysis. This paper study about a popular method to ascertain the performance level of a building is through pushover analysis, which yields results that indicate whether collapse occurs at the member or structure level. Performance-based design is used to evaluate the performance level of buildings subjected to earthquakes. Various approaches in nonlinear static analysis were developed to study the performance of a building. This assessment has taken into account a non-existing solid Rcc structure that is assumed to be located in Zone IV, as defined by IS 1893:2000, a classification of seismic zones in India. During the entire inquiry, brick work infills have been considered to be non-structural individuals. Systems for inelastic static static study include the Secant Method, the Displacement Coefficient Method, and the Capacity Spectrum Method. Pushover Analysis, a non-direct static approach, was used to examine the structure's weak points, building on static testing. The structure was recreated in SeismoStruct Version 5.2.2 using M20 cement and Fe415 steel support, as predicted in STAAD Pro v8i. After that, the research is carried out for 150% of the predetermined objective displacing for the structure to track individual yielding and the sufficiency of the core quality. The degree of damage suffered by the structure during the objective displacing is thought to represent the damage the structure would experience under configuration level ground shaking. Key Words: Pushover analysis, RCC structure, Pushover curve, drift velocity, STAAD.PRO, Earthquake structure.

Seismic performance of buildings during the Magnitude 7.3 Kermanshah, Iran Earthquake

In this paper, the findings and data of a large-scale reconnaissance mission following the November 12, 2017, M7.3 Kermanshah earthquake near the Iran-Iraq border are presented. The earthquake affected multiple cities in both countries and led to widespread damage and notable casualties and fatalities. The highest peak ground acceleration was recorded in Sarpol-e Zahab at 0.7g. As part of two trips, the data on nearly 1200 buildings in eight cities were collected by devising a sampling scheme to maximize the coverage of the survey, which was then employed to compile regional damage statistics. The spatial distribution of damage is presented for the entire region as well as various cities and neighborhoods in each city. The damage statistics are also disaggregated based on structural building, occupancies, and risk categories. The damage sustained by various categories of building components and contents is also assessed. In addition, the damage at the component level is closely examined for the structural and nonstructural components of severely damaged buildings to reveal the underlying causes that root in poor construction practices, lax enforcement of the building code, and inadequate seismic design provisions. Finally, the damage to hospitals in the region is investigated. This data, which can be augmented through a similar approach in the aftermath of probable future earthquakes, is key in calibrating the regional risk and resilience analysis of communities.

Seismic Fragility Curves of RC Buildings Subjected to Aging

A large number of existing reinforced concrete (RC) buildings have surpassed their anticipated service life and show signs of degradation due to aging; this degradation is a function of the construction practices adopted in the past as well as environmental conditions. This paper discusses seismic fragility and the risk assessment of RC structures, emphasizing the impact of corrosion due to concrete aging and the associated deterioration mechanisms. The literature on this topic is critically reviewed, and a methodology for studying the seismic fragility of deteriorated RC buildings is proposed. As a case study, a four-story RC building designed according to contemporary code provisions is examined. The investigation encompasses the derivation of fragility curves, considering critical parameters such as the corrosion rate, the initiation time, and the cover depth. The proposed approach enables the evaluation and quantification of the impact of corrosion mechanisms on the seismic performance of buildings.

Assessing the significance of nonlinear rotational behavior in high damping rubber bearings for seismic performance of base‐isolated RC frame building

AbstractUtilizing high‐damping rubber bearings (HDRBs) for seismic isolation significantly enhances building seismic performance. However, previous studies have often neglected the nonlinear rotational behavior of these bearings when assessing base‐isolated systems using HDRBs. This study introduces two numerical models of the HDRBs, each comprising six springs. The first model, referred to as the BIL model, assumes linear behavior for the rotational degrees of freedom of the bearings. The second model, referred to as the BINL model, accounts for the nonlinear rotational behavior. The parameters of the bearing shear springs and the rotational springs of the two models are calibrated using experimental data. In order to investigate the influence of nonlinear rotational behavior of HDRBs on the seismic performance of base‐isolated buildings, nonlinear time history analysis is conducted on a six‐story base‐isolated RC frame building. Comparative analysis between the BIL model and the BINL model covers bearing behavior, superstructure response, and energy dissipation distribution. Results indicate a significant influence of considering nonlinear rotational behavior on column bending moments. These findings provide crucial insights for enhancing seismic design strategies for base‐isolated buildings.

Machine Learning Prediction Model for Boundary Transverse Reinforcement of Shear Walls

Due to their roles as efficient lateral force-resisting systems, reinforced concrete shear walls exert a tremendous degree of influence on the overall seismic performance of buildings. The ability to predict the boundary transverse reinforcement of shear walls is critical to the seismic design process, as well as in the overall evaluation and retrofitting of existing buildings. Contemporary empirical models attain low predictive accuracy, with an inability to capture nonlinearity between boundary transverse reinforcement and different influencing variables. This study proposes a boundary transverse reinforcement prediction model for shear walls with boundary elements based on the demand of ductility. Using the extreme gradient boosting machine learning algorithm and 501 samples, some 52 input variables are considered, and a subset with six features is selected, monitored, and analyzed using both internal methods (gain and cover) and external methods. The results (R2=0.884) display superior predictive capacity compared with existing models. Interpretation and error analysis are performed. Safety analysis is conducted to obtain references for use in practical engineering. Overall, this study presents a more accurate tool for use in seismic design and provides references for the evaluation and retrofitting of existing buildings. Our contributions hold significant implications for enhancing the safety and resilience of reinforced concrete structures.

On the fragility of non‐structural elements in loss and recovery: Field observations from Japan

AbstractThe role of non‐structural elements (NSEs) in the seismic performance of buildings has been highlighted in past years. Research studies following state‐of‐the‐art methodologies generally find that when the structural collapse is not of significant concern, NSEs tend to dominate the repair costs and financial investment required in a building. This paper examines field observations from interviews and data collected from commercial buildings via structural health monitoring (SHM) following the 2018 Osaka earthquake in Japan. It suggests that fragility functions used in current methodologies for estimating NSE damage may not be entirely representative of the in‐situ reality and possibly underestimate actual damage. Additionally, interviews with building owners/managers indicate that the alarm and financial impact of NSEs was not as critical as anticipated, with much of the observed NSE damage not of serious concern and tolerable in many cases. This article provides discussion and insight into possible causes for these differences before discussing how current methodologies can benefit from these observations. It is believed that many of the fragility functions currently used to estimate NSE damage may not be representative because of differences in installation conditions and loading protocols used in experimental testing, possible interaction with other elements, variability in the quality of workmanship during installation and possible wear, tear and degradation during service. On the other hand, it is seen how SHM data recorded during seismic events may provide valuable data for an alternative means to develop fragility functions. Furthermore, it is seen that when building recovery states (RSs) other than the implicitly assumed ‘full recovery’ state used in guidelines like FEMA P‐58 are explored, the role of NSEs in direct monetary losses significantly reduces. This coincides with the field observations in Japan regarding the impact of NSEs and supports the recent developments in functional recovery on what building owners and occupants are prepared to tolerate post‐earthquake. It indicates that when discussing the relative importance of different building performance groups, it is vital that the expected RS is also stated, as for most decision‐makers following major events, functionality rather than full recovery remains the primary goal; hence, repairs and proactive measures should bear this in mind for more effective use of resources.

Seismic Performance Assessment of RCC Building with Podium

With the advancements in structural engineering, seismic performance of buildings can be adjudged on the basis of performance-based techniques. This paper presents the performance based seismic evaluation of buildings with podiums for varying ratios of tower area to podium area. The structural system of the building consists of shear walls and moment resisting frames. Buildings with podiums have been designed and analysed with and without connection between the tower portion and the podium portion for Seismic Zone IV, by carrying out response spectrum analysis as per IS 1893-2016. The structural responses have been compared in terms of diaphragm forces, base shear, time period, storey stiffness, storey shear, storey displacement etc. for the variations in number of podiums i.e., single, double & three podium levels. Performance-based seismic evaluation of the buildings has been carried out with podium and tower as a connected unit with varying ratios of 0.35, 0.45, and 0.55 of tower area to podium area i.e., by keeping the tower area constant and increasing the podium extents. Pushover analysis is carried out and comparison is done for the influence of podium on the non-linear behaviour of the structures.

Experimental testing of GCr15 bearing steel with different surface treatments as passive friction energy-dissipative shims

The seismic performance of buildings can be improved by adding supplemental damping using friction dampers. The friction behavior of the metallic shims becomes more stable with increasing surface hardness ratio between the friction pair. However, as hardness increases, metallic materials tend to become more brittle, which increases the risk of accidental failure. This study investigated the performance of a friction energy dissipator using bearing steel (GCr15) treated by a grinding-strengthening process, a special manufacturing technology for bearings steel commonly used in mechanical engineering. Two base materials, Q355 and B450, were additionally compared with GCr15. Each base material used three different surface treatments, i.e., cleaned surface (CS), sand-blasting (SB), and grinding-strengthen (GS) treatments. The surface hardness of Q355-GS, B455-GS, and GCr15-GS increased by 13.62 %, 17.38 %, and 19.71% compared to their base materials, while sand-blasting didn’t have an increased effect on surface hardness. The nine specimens were quasi-statically tested to investigate the effect of surface treatment on the friction behavior of the metallic shims. For the three Q355-like and three B450-like specimens, the wear mechanism mixed abrasive and adhesive wear. The GCr15-CS experienced contact fatigue failure, while the GCr15-SB and GCr15-GS exhibited abrasive wear resulting in standard rectangular hysteretic loops with a high degree of coincidence. The friction performance of GCr15-GS was the best among the nine friction shims, because it has less loss in friction coefficient and strength during fatigue loading, the least fluctuation in bolt force, and the smallest degradation and coefficient of variation in friction strength.

Stochastic-based vulnerability curves for the out-of-plane seismic safety assessment of URM walls

Earthquakes are a major cause of damage and human losses to the built environment, including cultural heritages, monumental buildings and historical centers. In the last decades, the seismic performance of buildings has received special attention due to the interest in the built heritage conservation and protection of human life, particularly with respect to masonry structures which have shown evidence of poor behavior once subjected to seismic loads. The present work contributes to the seismic safety assessment of the out-of-plane behavior of unreinforced masonry walls through a displacement-based approach, providing the capacity for different out-of-plane geometric indexes and its seismic response in different earthquake-prone regions. The analyses are conducted using a seismic probabilistic framework, considering the most common out-of-plane mechanisms, different material properties, various slenderness ratios, and a wide range of seismicity levels to cover the seismic hazard in Europe. The results presented can be useful for seismic safety assessment and to incorporate vulnerability models for seismic risk analysis.

Numerical Study on the Seismic Performance of Cold-Formed Steel Shear Walls with Steel Sheathing and Gypsum Board.

The cold-formed steel shear wall with steel sheathing has gained increasing popularity due to its excellent shear capacity. To extend the applicability of this system to multi-story residences, aside from experimental investigations on the shear walls, it is essential to conduct a comprehensive study on the seismic performance of buildings. In this paper, numerical simulations were conducted on specimens subjected to monotonic and cyclic loading. Subsequently, seismic analysis of mid-rise building models was also carried out to investigate the influence of the proposed shear wall on building seismic performance. The research findings indicate that this study's modeling method can effectively simulate the shear performance of the proposed shear wall under monotonic and cyclic loading. In addition, the proposed shear wall significantly enhances the structural stiffness and improves the seismic performance of the structure under seismic action.

Evaluating the Seismic Performance of Low-Rise Concrete Buildings Using Nonlinear Static Analysis

Evaluating the Seismic Performance of Low-Rise Concrete Buildings Using Nonlinear Static Analysis

Seismic performance and SSI effects of a two-storey RC school building during the 2014 Cephalonia, Greece, earthquake sequence

The response of a two-storey RC school building in the town of Argostoli, Cephalonia Island, Greece, during the seismic sequence of January and February 2014, is examined. The structure was built following an older generation of seismic codes dating from the 1950s, which provide limited strength and ductility against lateral loads. Despite the severity of ground shaking and the two successive events, the building suffered relatively minor damage, like most of the RC buildings in the town. Following a short presentation of some basic seismological, structural and geotechnical aspects of the seismic sequence, the paper focuses on the seismic performance of the structure at hand. To this end, a series of detailed non-linear static and time-history dynamic analyses are reported, which highlight the interplay of soil, foundation and superstructure in modifying the seismic demand. It is demonstrated that SSI had an unexpectedly important (detrimental) role in the behaviour of the structure, increasing its natural period by about 25% and aggravating ductility demand in almost all columns, despite the moderately soft soil conditions (average VS = 180 m/s). The results shed light on the seismic performance of the building and help drawing conclusions on the engineering effects of the 2014 Cephalonia earthquake sequence.

Effect of Different Types of Bracing Systems on Seismic Performances of High Rise Buildings: A Review

This work discusses the incorporation of bracing systems in RCC structures in India to mitigate earthquake impact. It explores how bracing techniques can create open spaces by eliminating interior columns. RCC bracing offers advantages in stiffness and stability compared to conventional methods. The study evaluates different RCC bracing systems in high-rise buildings using STAAD. ProV8i software and compares their seismic performance. X- Braced frames are found to be more efficient and secure during earthquakes than moment-resistant and V-braced frames.

Seismic Performance of Reinforced Concrete Buildings with Joist and Wide-Beam Floors during the 26 November 2019 Albania Earthquake

Beams with width greater than their depth and depth equal to the depth of the slab (concealed wide beams) are widespread in Reinforced Concrete (RC) buildings in Albania. A large number of RC buildings with wide beams were hit by a strong Mw6.4 earthquake on 26 November 2019. The earthquake hit two of the most densely populated areas in Albania and caused widespread damage to these buildings. This paper aims to provide an updated view on the seismic performance of buildings with wide beams in light of the new field data following the 26 November 2019 Albania earthquake. To this end, a thorough literature review including experimental and field observations from past earthquakes is presented and data from field visits in Albania are described. It was found that damage to the joists and wide beams themselves was limited, even when the buildings suffered significant non-structural or structural damage in other elements as a result of the earthquake. A discussion on the behavior of wide beam–column frames based on nonlinear structural analyses and tests from the literature is presented. Furthermore, the implications of the results of the analysis for the seismic performance of RC buildings are discussed and confronted with observations from the 2019 Albania earthquake. Based on the literature review, further experimental research on wide beams with longer and more realistic span lengths is recommended.

The Effect of Span-to-Height Aspect Ratio to The Damage Index Ratio of RC Buildings with Vertical Irregularity Setbacks

Many type irregularities exist in reinforced concrete frame buildings to accommodate the demand from architectural and aesthetic aspects. One of it is vertical irregularity setback. Its appearance affected the building seismic performance and the damage distribution. Previous researchers proposed equations to correlate between irregularity indices and damage index ratio of setback buildings. However, the aspect ratio between span and height were not included in the formula. This research presents the influence of span-to-height ratio to damage index ratio of the reinforced concrete buildings with setbacks. A set of 2D RC frames having setbacks are evaluated with nonlinear dynamic analyses under three seismic input motions. Several span-to-height aspect ratios were applied by changing the inter-story heights. The Park-Ang damage index was adopted to evaluate the damage index ratio between tower part and base part to represent the damage distribution and the inter-story drifts were observed to represent the building seismic performance. The result showed that under the same earthquake motions, the decrease in span-to-height ratio majorly increased the maximum inter-story drifts. The damage index ratio values between tower part and base part fluctuated, however the similar pattern of damage distributions between tower and base structure were obtained.

Influence of Masonry Infills on Seismic Performance of an Existing RC Building Retrofitted by Means of FPS Devices

The safety assessment of existing structures in areas with a relevant seismic hazard is one of the major topics for engineers since many existing reinforced concrete structures have been realized disregarding seismic design with minimal details with respect to present practice. In this context, seismic assessment is a primary issue in order to identify the best retrofitting solution with the aim of enhancing the efficiency of existing buildings. In recent years, with the aim to enhance the seismic behavior of reinforced concrete (RC) structures (with particular care to existing ones), the system of seismic isolation adopting friction pendulum (FPS) devices proved to be among the most diffuse and effective solutions. The purpose of this paper is to explore the effectiveness of the refurbishment using FPS with single concavity devices on the performance of one irregular existing RC building placed in a highly seismic area of central Italy. First, the geometric and material characteristics of the building have been determined within the approach based on the “knowledge levels”. Second, a suitable numerical model based on a fiber-modeling approach has been established using SAP2000, including relevant mechanical non-linearities. Then, a set of 21 natural seismic inputs, inclusive of 3 accelerations over vertical and horizontal directions, was adopted with the aim of performing non-linear (NL) dynamic simulations. The NL dynamic simulations have been performed considering the structural system, both inclusive and not inclusive of the FPS isolator devices. The influence of the actual distribution of infill masonry panels on the overall behavior of the structure has also been evaluated in both of the cases mentioned above. Finally, the outcomes deriving from the NL dynamic simulations were helpful in assessing the advantages of the intervention of retrofitting to improve the seismic performance of the building, highlighting the influence of masonry infills.

Seismic Collapse Risk Assessment of Low-Aspect-Ratio Reinforced Concrete Shear Walls Using the FEMA P695 Methodology

Several recent research studies have demonstrated that the seismic performance of low-aspect-ratio reinforced concrete (RC) shear walls (i.e., defined herein as walls with height-to-length ratios less than 2) has not been yet adequately quantified to allow for robust risk assessment. This is mainly attributed to the complex nonlinear flexure/shear interaction behavior of such walls, along with their wide spectrum of possible design parameters, leading to major discrepancies in their seismic performance. Despite this unique behavior, most building codes and design standards do not assign distinctive seismic performance factors for such walls. To address this, the main objective of the current study is to propose seismic performance factors for low-aspect-ratio RC shear walls when different wall geometrical configurations and design parameters (e.g., aspect ratios, axial load levels, and seismic design categories) are adopted. These factors are evaluated against the acceptance criteria of the FEMA P695 methodology for Quantification of Building Seismic Performance Factors. In this respect, a numerical model was developed and experimentally validated to simulate the seismic response of 36 low-aspect-ratio RC shear wall archetypes. The model was utilized to perform nonlinear static and dynamic analyses, and collapse fragility curves were then generated to assess the collapse risk of such wall archetypes following the FEMA P695 methodology. According to the methodology, the proposed seismic performance factors were assessed by quantifying the ratio between the median collapse intensity and the intensity of the maximum considered earthquake (MCE). The results showed that R factors of 2.0 and 3.0 for special low-aspect-ratio RC walls with low and high axial load levels, respectively, can limit the probability of collapse under the MCE and are subsequently able to meet the FEMA P695 acceptance criteria.

Seismic performance of buildings with novel self‐centering base isolation system for earthquake resilience

AbstractThis study presents a novel self‐centering (SC) base isolation system enabled by traditional lead rubber bearing (LRB) incorporating superelastic shape memory alloy (SMA) U‐shaped dampers (hereinafter referred to as SMA‐LRB). This system is particularly suitable for some important structures (e.g., hospital buildings) that require high seismic performance and rapid recovery of normal serviceability after a severe earthquake. The working mechanism of the SMA‐LRBs is first illustrated, followed by a comparative experimental study on the traditional LRB and the emerging SMA‐LRB. Test results confirm the satisfactory flag‐shaped hysteresis loops of SMA‐LRB associated with significantly reduced residual deformation under cyclic loading. Subsequently, a refined numerical modeling strategy for these bearings is developed. The seismic performances of the SMA‐LRBs are examined systematically through two comparative reinforced concrete (RC) frame buildings, namely, the traditionally isolated and the SC isolated cases under far‐ and near‐field earthquakes. Seismic fragility analyses are further carried out through incremental dynamic analysis (IDA). The seismic responses demonstrate that the SC isolated building can match or improve the behavior of the traditional isolated buildings. Compared with the considerable residual deformation of the traditional isolated system under some earthquake events, the SC isolated system exhibits negligible residual deformation that can significantly avoid normal serviceability disruption while achieving the high‐performance objectives. The SC base isolation system can provide a promising type of advanced seismic protection device for earthquake resilient design.

Studying and Analyzing the Seismic Performance of Concrete Moment-Resisting Frame Buildings

Nowadays, due to environmental changes, the condition of buildings can be in danger. In order to protect the performance of existing buildings, it is important to investigate the seismic behaviour of building structure subjected to earthquake excitation. In addition, it is important to study the advanced level of ductile design recommended by current codes. In the immediate future, lateral load resistance needs to be evaluated precisely. For the purpose of analyzing the seismic responses of reinforced concrete (RC) buildings in this project, 6- and 12-story frames of representative buildings are modeled in this research paper. The response spectrum analysis is deployed for a multi-degree-of-freedom system exposed to seismic waves (earthquake) in the City of Vancouver. Hence, the seismic nature of Vancouver City is emulated by the resulting response spectra using ground motion records (GMR). Ultimately, for concluding the average displacement as well as the base shear of the structures, a time-history analysis is investigated. In this regard, the SAP2000 and ETABS software are utilized for analyzing seismic performances. In addition, a comparison is presented between previous studies that used the IDARC2D software and the proposed results that used the ETABS software. It is found that the applied cases are not overlapping the limit of the NBCC 2015 Code. Consequently, after investigation, it is evident that the 3D software is much more accurate than the 2D software.

Seismic vulnerability assessment of a masonry structure and an FRP-strengthening proposal

This paper reports an approach to seismic performance evaluation for masonry structures using linear, nonlinear, and kinematic limit analyses. Considering the analysis results, a retrofitting proposal using fiber-reinforced polymer composites was made. All examinations and strengthening interventions were carried out for a masonry restaurant building currently in use. First, a structural model of the building was prepared based on the current seismic codes. In the second stage, the seismic performance of the building was determined using global and local analysis approaches. The shear force and relative story drift ratios were compared using the limit values given in the seismic code. In addition, local failure mechanisms were determined. Accordingly, the structural strength of the building was found to be insufficient. Therefore, a fiber-reinforced polymer -strengthened design proposal was presented. In order to determine the effectiveness of the proposed strengthening, linear and nonlinear analyses were made based on the strengthened state. In this study, the analysis methods used to assess the seismic performance of a masonry building and strengthening proposal can make significant contributions to construction engineers and architects for the rehabilitation of masonry structures.