Pushover Analysis Research Articles

Seismic performance and cost comparison of RC moment resisting and dual frames using UBC 97 and IBC 2021

The transition from the Uniform Building Code (UBC-97) to the International Building Code (IBC-21) marked a major shift in the definition of seismic hazard. The term “seismic hazard” in the form of peak ground acceleration (PGA) is replaced by spectral acceleration. This paper investigates the effect of using new seismic hazards on the structural performance of reinforced concrete (RC) buildings. It also looks into the financial impact on the capital costs of new buildings. Useful insights are made to understand the structural performance and financial impact of adopting IBC 21 for structural design in contrast to UBC 97. This study was carried out from the perspective of a developing country, Pakistan. Reinforced concrete moment resisting and dual frames are used as the main structural system of a typical 7-story residential building to investigate the aforementioned effect. The frames are assumed to be located in two locations with high and low seismic hazards. The effect on structural performance is investigated via nonlinear pushover analysis. Financial impact is judged mainly through cost estimation for steel and concrete. A detailed discussion is also presented on the seismic design guidelines in both codes.

Seismic Performances of Masonry Educational Buildings during the 2023 Türkiye (Kahramanmaraş) Earthquakes

Huge losses of life and property occurred as a result of two independent catastrophic earthquakes on 6 February 2023 in the Eastern Anatolian Fault Zone, where no significant earthquake has occurred in approximately 500 years. The earthquakes, whose epicenters were in the Pazarcık and Elbistan districts of Kahramanmaraş province at 9 h intervals, had magnitudes of Mw = 7.7 and Mw = 7.6 and caused different levels of structural damage, especially in masonry-style structures in rural areas. In this study, the damage that occurred in masonry village schools, especially in rural areas, during these two earthquakes was evaluated in terms of the characteristics of the earthquake and within the scope of civil engineering, and the causes of the damage were discussed. The damage levels of the masonry schools examined were classified using the European Macroseismic Scale (EMS-98). Information about the Kahramanmaraş earthquakes was given and structural analyses were carried out for a widely used reference school building. The school building block was analytically modeled, and its seismic load-bearing capacities were predicted through pushover analysis in TREMURI software. The study also includes repair and strengthening recommendations for such structures.

Nonlinear Soil–Pile–Structure Interaction Behaviour of Marine Jetty Structures

Nonlinear soil–pile–structure interaction (SPSI) phenomena are known to play a vital role in the response of bottom-fixed marine structures. For such structures, these phenomena are commonly considered by the imposition of p-y, τ-z, and q-z springs, representing the lateral and axial shaft and axial base soil resistances, respectively. The importance of each resistance mechanism depends on the type of foundation system, with only very limited studies investigating their roles in the response of piled marine structures, such as jetties. Within this context, this study presents numerical three-dimensional pushover analysis results for two marine jetties, a smaller model with four piles and a larger model supported by twenty-four piles. SPSI effects are considered through p-y, τ-z, and q-z springs, the behaviours of which are determined by following commonly employed procedures. The structures’ responses are investigated under the influence of various assumptions regarding the behaviours of springs, as well as steel plasticity. The current investigation underscores the substantial influence of the axial soil–pile interaction on the response of the jetty, particularly in terms of its failure mode. Moreover, it demonstrates the importance of incorporating p-y springs, even though the choice between their linear or nonlinear constitutive behaviour is found to be less critical. Finally, the study concludes that the behaviours of the springs significantly affect the system’s ductility and the degree of steel yielding in the piles, while also highlighting the unconservative influence of neglecting SPSI phenomena.

Investigation of RC structure damages after February 6, 2023, Kahramanmaraş earthquake in the Hatay region

From a tectonic perspective, Türkiye is a geographical region known for its high seismic activity, with some of the most active faults in the world. On February 6, 2023, two consecutive earthquakes with magnitudes of Mw 7.7 and Mw 7.6 struck Kahramanmaraş within a remarkably short time span of 9 h. This event stands out as a rare and unprecedented tectonic occurrence in terms of seismicity and tectonic activity over the past 100 years. The impact of these two major earthquakes on the region's reinforced concrete structures was significant, resulting in severe damage and the collapse of numerous buildings. It is of utmost importance to investigate and examine the design flaws and underlying factors that contributed to the damage observed in the reinforced concrete structures affected by these earthquakes. Such research will not only contribute to the improvement of structural design, seismic regulations, and quality control measures during construction but also enhance our understanding of earthquake engineering. In this study, an in-depth field investigation was conducted on reinforced concrete structures in Hatay, one of the regions most affected by the Kahramanmaraş earthquakes. The damages occurring in the buildings were documented through a detailed field survey and analyzed. A total of 540 reinforced concrete structures in the Hatay region were extensively examined, and the damages that occurred in these structures were photographed and interpreted to understand their underlying causes. Subsequently, based on the findings from the field investigation, a structural model was designed that incorporated the most significant design and construction errors responsible for the damages observed in the 540 examined structures. The devised model was subjected to static push-over analysis and nonlinear dynamic analysis using the SAP2000 finite element software, and the results obtained were interpreted.

Drift damage limit estimation based on cracks of concrete gravity dam considering dam-foundation interaction

ABSTRACT This study focuses on estimating the drift limits associated with different damage states of concrete gravity dams, emphasizing the role of cracks along the dam base and the interaction between the dam and its foundation. Employing a comprehensive framework and nonlinear pushover analysis, the research accounts for uncertainties in concrete and foundation material parameters, evaluating three distinct models with varying height-to-base width ratios (1, 1.25 and 1.5) through 20 runs based on central composite design. The findings indicate that as the height-to-base width ratio increases, the concrete gravity dam demonstrates greater resilience against lateral movements, highlighting its ability to withstand larger drifts without incurring damage. Additionally, the study’s proposed mathematical model accurately predicts the drift limits across different levels of damage, facilitating a comprehensive understanding of the structural behavior and its implications for seismic risk assessments. The research underscores the significance of considering the varying degrees of damage and their impact on the concrete gravity dam’s operational capability and safety, offering crucial insights for ensuring the integrity and stability of these essential infrastructures.

Seismic response and ambient vibrations of a Mediaeval Tower in the Mugello area (Italy)

AbstractThis paper describes the experimental campaigns on the Tower of the Palazzo dei Vicari in Scarperia, a village in the Mugello area (Tuscany) exposed to high seismic hazards. The first campaign was carried out from December 2019 to January 2020, and the Tower underwent the so-called Mugello seismic sequence, which featured an M 4.5 earthquake. Other ambient vibration tests were repeated in June 2021 and September 2023 when another seismic sequence struck the area near Scarperia. These tests aimed to characterise the Tower’s dynamic behaviour under ambient and seismic excitations and check the response of the Tower over time. The experimental results were then used to calibrate a finite-element model of the Tower and estimate its seismic vulnerability. Several numerical simulations were conducted on the calibrated model using the NOSA-ITACA code for nonlinear structural analysis of masonry buildings. The dynamic behaviour of the Tower subjected to a seismic sequence recorded in 2023 by a seismic station at the base was investigated by comparing the velocities recorded along the Tower’s height with their numerical counterparts. Furthermore, several pushover analyses were conducted to investigate the collapse of the Tower as the load’s distribution and direction varied.

Pushover Analysis of G+20 RCC Structure with Horizontal Irregularity

Pushover Analysis of G+20 RCC Structure with Horizontal Irregularity

Non-linear seismic behavior of historic Adana Great Clock Tower

In this study, the non-linear seismic behavior of the historic Adana Great Clock Tower was investigated. The dynamic characteristics (natural frequencies and mode shapes) of the Clock Tower were determined by operational vibration tests. The finite element model of the Clock Tower was manually updated in the light of the experimentally obtained dynamic characteristics. For the updated finite element model, pushover analyses and non-linear time history analyses were performed. Incremental pushover analyses were performed in the x and y directions proportional to the first lateral displacement modes of the Clock Tower in the x and y directions. The time history analyses took into account the Adana-Ceyhan (1998) earthquake acceleration records. Each of the two horizontal components of the earthquake acceleration records was separately scaled according to the design spectrum defined in TBEC-2018 for earthquake levels with a 10 % and 50 % probability of exceedance in 50 years. These scaled earthquake acceleration records were applied to the structure. The two scaled horizontal components for the same earthquake level were rotated 90° and reapplied to the structure. As the response quantities, displacement, base shear force and plastic strains were evaluated.

Composite floor slab effect on seismic performance of steel-framed-tube structures with shear links

High-strength steel-framed-tube structures with low-yield-point shear links (SFT-RLYPSL) exhibit exceptional lateral and torsional stiffness, coupled with significant energy dissipation capacities. This study aims to investigate teh influence of composite floor slabs on the seismic performance of these structures. Expanding on previous research concerning SFT-RLYPSL, this paper presents a simplified numerical model for the SFT-RLYPSL, incorporating the influence of the composite floor slab. The developed model employs the steel4 constitutive relation to accurately depict the behavior of low-yield-point steel. Furthermore, the simplified numerical model utilizes two-node link elements to simulate shear links and integrates composite beams to represent the influence of the composite floor slab. Using this simplified model, elastic-plastic pushover analysis is performed on five distinct SFT-RLYPSL structural cases, and nonlinear time-history analysis is conducted on three structural configurations. The investigation explores various aspects of the seismic performance of SFT-RLYPSL, including modal behavior, pushover curves, progression of overturning failure, time-history roof displacements, inter-story drift angles, base reactions, inter-story shear, failure modes, residual inter-story drift angles, and the manifestation of shear lag phenomena. The findings suggest that incorporating the composite floor slab effect enhances initial stiffness and peak load capacity in pushover analysis, leading to distinct three-stage pushover curves. During nonlinear time-history analysis, the composite floor slab effect increases structural stiffness, decreases roof displacements and inter-story drift angles, while simultaneously increasing base reactions, worsening component damage, and raising collapse risk. Nevertheless, its influence on residual inter-story drift angles remains relatively minor, with a mitigating effect on the shear lag phenomenon. Importantly, the degree of this impact varies with alterations in floor slab thickness and seismic intensity, highlighting the critical importance of considering the composite floor slab effect in structural design deliberations.

Determination of the In-Plane Behavior of Masonry Walls Using the Truss Model

ABSTRACT The diverse characteristics of masonry structures make it difficult to determine their behavior. The development of numerical methodologies using various approaches and assumptions reflects the need for adaptable methods to accommodate these diverse structures. This study focuses on a novel simplified approach for analyzing masonry walls. The proposed method uses truss elements with a well-known theoretical background to elucidate the load-bearing capacity, damage formation and its causative factors, and failure mechanics of masonry piers within a plane. Five masonry wall samples from three different studies were used to validate the accuracy of the proposed approach. Pushover analyses were performed using software with nonlinear analysis capabilities, which was developed in the Python programming language. Consequently, the obtained results were compared with the literature data. This method provides initial expectations such as simplification and consistency, making it a potential alternative for the preliminary assessment of masonry structures.

Finite element modeling of composite plate shear walls/concrete-filled (C-PSW/CF)

A Composite Plate Shear Wall/Concrete Filled (C-PSW/CF) is a “sandwich” type of construction by which concrete (without rebars) is enclosed between steel plates connected by tie bars. Since this system is relatively new, researchers as well as practicing engineers sometimes need to develop nonlinear model of these walls to be able to run pushover analyses, cyclic analyses, and seismic response analysis of C-PSW/CF. Different methods can be used for such non-linear analysis, as a function of project needs and computational resolution desired. This paper focuses on finite element modelling; it describes the details of the LS-DYNA models of the C- and T- shaped C-PSW/CF specimens tested in SEESL at University at Buffalo and shows the comparison between test data with the results of finite element analysis of specimens. As such, the objective of this paper is to present the details of a model used to replicate the hysteretic behavior of the tested specimens, and then answers questions that cannot be investigated or measured from tested specimens. More specifically, this allowed to quantify the respective contributions of steel and concrete to the total flexural strength throughout the entire cyclic history, where (for example) steel contributed to 54 % of the total flexural strength in the positive direction during the initial cycles of hysteretic response, degrading to 45 % at the onset of local buckling in the web, but recovering to 80 % upon strength global strength degradation of the wall.

Surrogate models for seismic and pushover response prediction of steel special moment resisting frames

For structural engineers, existing surrogate models of buildings present challenges due to inadequate datasets, exclusion of significant input variables impacting nonlinear building response, and failure to consider uncertainties associated with input parameters. Moreover, there are no surrogate models for the prediction of both pushover and nonlinear time history analysis (NLTHA) outputs. To overcome these challenges, the present study proposes a novel framework for surrogate modelling of steel structures, considering crucial structural factors impacting engineering demand parameters (EDPs). The first phase involves the development of a process by which 30,000 random steel special moment resisting frames (SMRFs) for low to high-rise buildings are generated, considering the material and geometrical uncertainties embedded in the design of structures. In the second phase, a surrogate model is developed to predict the seismic EDPs of SMRFs when exposed to various earthquake levels. This is accomplished by leveraging the results obtained from phase one. Moreover, separate surrogate models are developed for the prediction of SMRFs’ essential pushover parameters. Various machine learning (ML) methods are examined, and the outcomes are presented as user-friendly GUI tools. The findings highlighted the substantial influence of pushover parameters as well as beams and columns’ plastic hinges properties on the prediction of NLTHA, factors that have been overlooked in prior studies. Moreover, CatBoost has been acknowledged as the superior ML technique for predicting both pushover and NLTHA parameters for all buildings. This framework offers engineers the ability to estimate building responses without the necessity of conducting NLTHA, pushover, or even modal analysis which is computationally intensive.

Contrastive Investigation of High rise building with distinctive infill wall by Pushover analysis

Pushover analysis is a method that uses simple nonlinear techniques to predict seismic structural deformations. Today, we use masonry infill in reinforced concrete (R/C) frames for architectural, aesthetic or economic reasons. In this project, we need to study the effect of backfill on the damage structure of the reinforced concrete frame. The main purpose of this study is to show that adding walls to the reinforced concrete frame can increase the strength and stiffness of seismic resistant structure loads and increase the feedback for strength and stiffness analysis.These instructions strictly comply with FEMA-356. In this project, we use three types of bricks: red brick, fly ash brick, deep brick and siporex brick. Taking the output of non-linear analysis, we compare layer V/S i) Base Shear, ii) Storey Displacement, iii) Floor Shift Base Shear V/S Attack and Observe Spectrum Acceleration V/S spectral function . We also use ETABS 2017 software to study the effects of bare shear walls.. Key Words: Pushover Examination, Brick infill, FEMA-356, Displacement, Float, Shear Divider, ETAB-2017

Effects of enhanced confinement on cyclic behavior of concrete bridge columns with partially unbonded seven-wire steel strands

The effects of enhanced confinement on the proposed bridge columns under lateral cyclic loading were investigated in this research by testing large-scale column specimens. The proposed column used nonprestressed partially unbonded seven-wire strands as elastic elements to increase the post-yield stiffness of the column to reduce the residual displacement under seismic loads. The enhanced confinement included rectilinear transverse reinforcement with an increased amount (specimen CSCR) and reduced spacing or innovative five-spiral reinforcement (specimen CSCS). Test results showed that all the specimens exhibited a positive post-yield stiffness ratio of 3.5–6.4 %. However, the enhanced confinement reduced the post-yield stiffness by 42–45 % but increased the lateral strength of the column, which is beneficial for controlling the residual displacement. The enhanced confinement did not affect the drift ratio when the positive post-yield stiffness ended (6 %) but significantly increased the deformation capacity by 15–31 % and the energy dissipation capacity by 37–63 % of the column. Even with a smaller amount of transverse reinforcement, the specimen with the innovative five-spiral reinforcement showed deformation and energy dissipation capacities better than the other specimens with conventional rectilinear transverse reinforcement. A pushover analysis model was developed and modified to better account for the effect of the enhanced confinement and the strand slip, and to consider the end point of positive post-yield stiffness. The comparison with the test result showed that the proposed pushover model well captured the envelope responses of the specimens. Finally, a simplified method was proposed for estimating the moment strength of the proposed column.

Design and Nonlinear Dynamic Response of a Steel Stack

AbstractIndustrial stacks are built in order to reduce atmospheric pollution and release gases to the higher level of the atmosphere. Since they are high and slender structures, they are significantly affected by lateral forces, in particular, induced by winds and earthquakes. This paper aims to summarize the design principles for steel stacks given in the international standards, codes and specifications considering the evaluation of the results from the investigation on nonlinear dynamic response of a typical steel stack subjected to the earthquake. For this purpose, a typical self-supporting steel stack has been designed and its performance under earthquake and wind forces has been investigated in terms of the applied design principles, such as the displacement limit and the potential plastic deformations. The study is accomplished by using finite element models employing nonlinear time history and pushover analyses. The numerical results are presented particularly by considering the design principles used for the model. The results show that wind loads considered are more pronounced in the design of industrial steel stacks than earthquake especially in terms of limiting top displacement. The flue openings which reduce strength and lateral stiffness of the stack web is significantly effective in the lateral behavior of the stack. Moreover, the principles considered are found applicable for the design of such steel stacks. Based on the results from nonlinear time history analyses, no yielding and plastic deformation are detected along the stack.

Assessment of RC Frame Structure under Different Seismic Condition

Abstract: Structures in seismic zones are especially prone to collapse during significant ground motion occurrences. This susceptibility is sometimes linked to flaws in seismic design principles, notably in the selection of suitable structural systems. Equivalent static analysis, which is often employed in seismic design, may not accurately account for the structure's strength and stiffness. As a result, ground floor columns may become highly reinforced, thereby lowering ductility, and causing poor performance. This thesis offers a parametric study of an RC frame structure developed for various seismic zones. The finite element software is used to model the structure to investigate performance levels. Pushover analysis was performed to determine the structure's seismic capacity and behavior under various seismic conditions. Parametric research employing RC Frames with demand variation was done to investigate the structure's behavior in different seismicity zones across the country

Contrastive Investigation of High-Rise Building with Distinctive Infill Wall by Pushover Analysis

Contrastive Investigation of High-Rise Building with Distinctive Infill Wall by Pushover Analysis

Analisis Perkuatan Kolom Lingkaran Pada Bangunan Soft-Story Menggunakan Steel Jacketing Dengan Pendekatan 2D

Collapse due to soft-story is often encountered in Indonesia. The collapse mechanism caused by soft stories is very dangerous, causing severe damage even collapse to the building structure. Steel jacketing is one of the means to strengthen the column which is considered effective in increasing the strength and stiffness of the reinforced elements hence soft story collapse in buildings can be prevented. The aim of this research is to evaluate the behavior of the existing building structure before strengthening the columns using limit analysis and pushover analysis and to determine the effect of strengthening columns with steel jacketing on the behavior and the performance of the structure. In this research, the existing structure is simulated to experience design errors and is modeled as a 2D portal with the function of a 4-story school building. From the results of the limit analysis, the existing structural model has the potential to experience a local collapse mechanism, followed by the potential for soft story collapse on the 1st floor. From the results of the pushover analysis, the existing structural model experiences the soft story mechanism and does not show performance points as required by FEMA 440. After carrying out this strengthening the column with steel jacketing, the structural model shows a better failure mechanism and the element performance obtained after strengthening is in the Immediate Occupancy (IO) range

Evaluation of plastic hinge length in RC shear wall connected with floor slabs

Traditionally, seismic design focuses on inelastic behavior at the base of isolated shear walls. Yet, in multistoried RC wall-frame buildings with interconnected shear walls and floor slabs, significant inelasticity occurs at wall-slab junctions. This interaction greatly enhances the structure's seismic capacity. Previous studies overlooked this interaction, concentrating instead on isolated walls. The extent of inelastic action in a wall connected with floor slabs has not been studied extensively in the past. In the present study, the extent of the zone of inelastic behavior is studied at the wall-slab junction region by carrying out displacement based nonlinear static analysis of the wall-slab assemblages under monotonic as well as cyclic loads. A parametric study is carried out by varying the wall panel aspect ratio and axial load on walls. It is observed that this interaction using nonlinear static analysis, revealing increased curvature demand and localized damages at the junctions. It is observed that the extent of tensile damage at the junction region remains consistent across different axial load levels at the maximum drift level. Analytical expressions for plastic hinge length are proposed, crucial for refining seismic design strategies. The plastic hinge equation derived from pushover analysis yields values approximately 1.34 times higher than those obtained from cyclic loading.

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.