Results Of Incremental Dynamic Analysis Research Articles

Seismic response of expanded polystyrene (EPS) sandwiched concrete panels system in buildings: Damage distribution and correlation analysis of parameters

Lightweight wall panels and connectors between them and load-bearing structures are often significantly damaged during moderate-intensity seismic events. However, generally applicable methods and models for predicting and assessing the damage are lacking. A seismic analysis and assessment framework for the interaction among lightweight partition wall panels, energy-dissipating connectors, and main structural elements was established via the Maximum Information Coefficient method. Experiments and numerical simulations were conducted to investigate the nonlinear behavior and hysteresis-based energy-dissipation features of connectors in Expanded Polystyrene sandwiched concrete panels. A system model incorporating lightweight wall panels, connections designed to absorb energy, and load-bearing structures is proposed to elucidate their collaborative interactions. The distribution pattern of seismic damage in the Expanded Polystyrene sandwiched concrete panels system was also investigated. Based on the characteristics of the incremental dynamic analysis results, a correlation evaluation of the seismic parameters and structural damage was conducted using the refined Maximum Information Coefficient method. The proposed analysis framework can be used for the damage evaluation and prediction of assembled nonstructural elements.

Time-dependent risk-targeted seismic design of RC moment-resisting frames under corrosive environment

‎Earthquake and corrosion are two factors that threaten reinforced concrete structures in the coastal areas of southern Iran. Taking into ‎account both hazards in designing of structures in these areas, apart ‎from the significant reduction in ‎loss of human lives, can minimize the economic damages. In ‎Iran, the design of newly built buildings ‎is based on seismic hazard maps in the design codes ‎based on a fixed return period of 475 years. Using this ‎traditional approach, results in an unequal risk level. This ‎justifies the risk-targeted design approach and developing ‎risk-targeted hazard maps which leads to a ‎uniform level of risk in the national scale. In this paper, intermediate ‎Reinforced Concrete ‎moment-resisting frames (RC MRFs) under corrosive environment are studied in ‎four important port cities in Iran ‎using ‎risk-targeted approach and in doing so, the design-based peak ground ‎acceleration (PGAs) of these cities is corrected. Based on the results of incremental dynamic analysis (IDA), the risk-targeted PGAs (PGARs) were ‎derived and the correction coefficients for PGAs ‎based on EMME14‎‏ ‏‏‎(CR-EMME14) and Standard 2800 (CR-St2800) is calculated. The average amount‎ PGARs was between 0.216 g and 0.585 g and the correction ‎factors were from 0.72 to 1.951. ‎The comparison between correction coefficients obtained for the ‎buildings damaged by corrosion, ‎indicate that current PGAs for the studied cities, are not sufficient for the seismic demands. ‎ The ‎results also indicate that by increasing the time after corrosion ‎initiation the correction factors ‎for PGAs increase which clearly shows the ‎importance of risk-targeted ‎approach in the seismic design of structures exposed to corrosive environment. ‎ ‎

Vibration control of an eleven-story structure with MR and TMD dampers using MAC predictive control, considering nonlinear behavior and time delay in the control system

In the last two decades, model predictive control has made significant progress in research and industrial process control. This achievement is through the high ability of model predictive control to solve industrial process control problems in the time domain. It is applicable in many control systems, such as delayed systems, univariate and multivariable systems, non-minimum phase systems, and unstable systems. This strategy is essentially for controlling delayed systems. It is possible to create a time delay in transmitting structure movement data in the systems that use sensors and receivers of sensor-recorded data, which is a factor to reduce the efficiency of the control system and even the instability of the structure. In this study, to investigate and compensate the effect of time delay in the hybrid vibration control system, an 11-story structure with a tuned mass damper and an MR damper was used by model algorithmic control (MAC) and nonlinear behavior of the structure in the control process. The linear and nonlinear structural models are created in OpenSEES, the control system in MATLAB; and the TCP/IP connection method was used to connect two programs. The fuzzy decision system is based on accelerating and decelerating movement. The structure has been subjected to seven earthquakes with maximum accelerations of 0.1 g to 1.0 g with an incremental step of 0.1 g. According to the results of incremental dynamic analysis, the average percentage of the fuzzy control system performance reduction, considering the time delay, is 15.28% and 38.57% for the maximum displacement and base shear in the linear structure, and 8.04% and 5.97% for the nonlinear structure, respectively. The assumed time delays have been effectively overcome using the model algorithmic control system (MAC), determining the prediction horizon of the structural behavior, and optimizing the control force in the control horizon. The performance of the MAC control system has been better than the fuzzy control system and the passive control with TMD. The average improvement percentage of the results of the maximum linear and nonlinear structural displacement response is respectively equal to 10.2 and 11.8 with the MAC control system, compared to the fuzzy control system without time delay. For the maximum base shear, it is equal to 8.32 and 2.49, respectively.

Seismic performance of hybrid coupled shear walls

AbstractHybrid Coupled Shear Walls are an innovative seismic‐resistant system that aims at merging the advantages of the classical Coupled Shear Walls with the dissipative capacity and easy‐to‐repair characteristics of steel elements. They are constituted by a reinforced concrete wall connected to two side steel columns by dissipative steel links. Depending on the stiffness/strength of the links, it is possible to obtain different distributions of the seismic forces between the wall and the columns. As resulting from previous research activity on this topic, the seismic behavior of this structural system can be strongly influenced by the higher modes, especially for mid/high‐rise buildings, making classical pushover analyses unable to catch the correct behavior. In this regard, the paper presents the comparison between the results of Incremental Dynamic Analyses and of different Pushover Analyses, giving indications about a more reliable procedure for the assessment of the seismic performance through suitable pushover analysis.

Numerical analysis of inclined demountable precast concrete walls with rocking-based composite columns for seismic protection of building structures

With the aim of simultaneously reducing all seismic demands, this paper proposes a novel structural system comprising inclined demountable walls with rocking base composite columns (IDWC). The proposed IDWC system combines the concepts of using inclined demountable walls in each story and rocking-based concrete filled steel tube (CFST) columns as the wall boundary elements. In particular, through inclined walls, the number of walls in each story is reduced, while with the use of rocking CFST columns, damage to the boundary elements can be mitigated. In total, 18 two-dimensional numerical models are developed and static as well as dynamic analyses are conducted to evaluate the performance of conventional and demountable wall systems of 4-, 10- and 15-stories height. For each height, 4 IDWC models, with various wall arrangements, and a vertical demountable wall model are analyzed and compared with a conventional reinforcement concrete wall model. For the studied models, micro and macro numerical models are developed and verified through experimental data. After performing cyclic and time history nonlinear analyses, it is shown that IDWC models have lower initial stiffness and higher energy dissipation capacity than the conventional model. According to these results, inter-story drift, floor acceleration, and base shear in IDWC models are reduced by up to 30%, 41%, and 45%, respectively, compared to the conventional model. Also, it is demonstrated that with the use of rocking CFST columns, the wall boundaries remain undamaged, which ensures any residual drifts after severe earthquakes are insignificant. Meanwhile, as the incremental dynamic analysis results show, the collapse capacity of IDWC models is up to 53.5% higher than that of conventional models.

Seismic damage characteristics of high arch dams under oblique incidence of SV waves

This study investigates the seismic damage characteristics of high arch dams considering the oblique incidence of seismic waves. Based on the dynamic implicit finite element method, a viscous-spring artificial boundary is applied to consider radiation damping of the infinite foundation, the seismic wave input is converted into an equivalent nodal force of the artificial boundary, and the equivalent nodal loads of the wave input under oblique incidence of the SV wave is deduced. Taking JP Ⅰ arch dam as an example, combined with the concrete damaged plasticity (CDP) model, the nonlinear dynamic response of the dam under 25° oblique incidence of the SV wave is conducted considering the geometrical nonlinearity of contraction joints and the dynamic mechanical properties of concrete materials. Based on the incremental dynamic analysis (IDA) method, the relative displacement and transverse joint opening are selected as the damage measures for fragility analysis of the arch dam. According to the damage distribution from the analysis of a large number of seismic time-history responses, the damage levels of the arch dam are classified. Three limit states of slight damage, moderate damage and severe damage are proposed for the arch dam. The average responses of the 10 earthquakes are considered as the limit values to quantitatively describe the damage of the arch dam. By fitting the results of incremental dynamic analysis, the seismic probabilistic demand model and seismic fragility curves for the two damage measures to predict the probability of the arch dam reaching damage levels under different seismic actions have been established. The fragility curve shows that the probability of severe damage is almost zero under the maximum design earthquake (PGA = 0.1971 g) and less than 5% under the maximum credible earthquake (PGA = 0.2299 g). It is concluded that JP Ⅰ arch dam has a high degree of safety redundancy and fully satisfies the “two levels” design requirements.

Seismic design parameters (R, Cd, and Ω0) for uncoupled composite plate shear walls−concrete filled (C‐PSW/CF)

AbstractComposite Plate Shear Walls−Concrete Filled (C‐PSW/CF) are an innovative seismic force resisting system recently adapted for building applications. The walls consist of parallel steel faceplates connected with tie bars and filled with concrete. This paper summarizes the results of a recent FEMA P695 study completed to verify seismic design parameters for uncoupled C‐PSW/CFs with rectangular flange plate boundary elements. Seven archetype structures were: (i) designed, (ii) modeled using a benchmarked fiber‐based finite element analysis approach, (iii) subjected to nonlinear pushover analysis, (iv) and to incremental nonlinear dynamic analysis to failure for 22‐sets of scaled ground motions, and (v) the results were statistically analyzed to assess performance. These structures ranged from three (3) to twenty‐two (22) stories and included both planar and C‐shaped configurations. As part of this design process, recommendations for stiffness approximations for linear analysis of C‐PSW/CFs were developed. Additionally, these nonlinear incremental dynamic analysis results were post‐processed to determine the rotation and strain demands at the base of these structures at the design basis, maximum considered, and failure level earthquakes. These results showed that the rotation and strain demand at failure level earthquakes were comparable regardless of the ground motion. Ultimately, this FEMA P695 approach verified the R factor of 6.5, Cd factor of 5.5, and Ω0 of 2.5 for C‐PSW/CFs with boundary elements.

Seismic behavior and nonlinear analysis of Hybrid Coupled Shear Walls

Hybrid Coupled Shear Walls are an innovative seismic-resistant system that aims at merging the advantages of the classical Coupled Shear Walls with the dissipative capacity and easy-to-repair characteristics of steel elements. They are constituted by a reinforced concrete wall connected to two side steel columns by dissipative steel links. Depending on the stiffness/strength of the links, it is possible to obtain different distributions of the seismic forces between the wall and the columns. As resulting from previous research activity on this topic, the seismic behavior of this structural system can be strongly influenced by the higher modes, especially for mid/high-rise buildings, making classical pushover analyses unable to catch the correct behavior. In this regard, the paper presents the comparison between the results of Incremental Dynamic Analyses and of different Pushover Analyses, giving indications about a more reliable procedure for the assessment of the seismic performance through suitable pushover analysis.

Endurance time analysis of seismic performances of long-span continuous rigid-frame bridges with corrugated steel webs

The seismic performances of continuous rigid-frame bridges must be evaluated efficiently and accurately using simplified methods during their design and strengthening. As a simplified method to evaluate the seismic performances of bridges, the endurance time method can be used to simulate the complete process of the collapse of an intact bridge via nonlinear time history analysis. The endurance time method is a novel approach of generating seismic acceleration time steps, which allow engineers and researchers to obtain maximal information from the states of the structures with the lowest computational cost. The Fei-Long Bridge—a long-span continuous rigid-frame bridge with corrugated steel webs—has the largest span of this kind in the world and is situated in a medium-risk seismic zone. In this study, we investigated the applicability and accuracy of the endurance time method to estimate the seismic performance of the bridge. Three endurance time accelerograms were generated as seismic inputs based on the design response spectrum provided by the Chinese specifications for the seismic design of highway bridges. In addition, 16 natural far-field and 16 natural near-fault ground motions were selected for incremental dynamic analysis. The seismic response characteristics of the bridge obtained by the endurance time method and incremental dynamic analysis were compared. The results of the endurance time method are observed to be within the envelope of the incremental dynamic analysis results, with an average error lower than 5%, and the median value of the endurance time method agrees well with the mean curve of the incremental dynamic analysis results. Therefore, the endurance time method can be used as a novel simplified and efficient method to evaluate the seismic performances of continuous rigid-frame bridges with corrugated steel webs.

Effects of Ground Motion Duration on the Seismic Performance of a Two-Storey Balloon-Type CLT Building

The effects of long duration ground motions on the seismic performance of a newly constructed two-storey balloon-type cross-laminated timber (CLT) building located in Vancouver, Canada, was studied. A three-dimensional numerical model of the building was developed in OpenSees. The connection and shear wall models were validated with test data. Twenty-four pairs of long and short duration records with approximately the same amplitude, frequency content, and rate of energy build-up were used for nonlinear dynamic analyses. Fragility curves were developed based on the results of incremental dynamic analysis to assess the building’s collapse capacity. At design intensity level, ground motion duration was shown not to be a critical factor as the difference in inter-storey drift ratio between the two sets of records was negligible. However, due to the larger number of inelastic cycles, the long duration motions increased the median probability of collapse by 9% when compared with the short duration motions. Further research is required to evaluate the duration effects on taller and platform-type CLT buildings.

Performance-based seismic design and assessment of multi-storey CFS strap-braced frames

Cold-formed steel (CFS) structures typically rely on diagonally braced stud walls to withstand lateral forces. While the response of CFS single-wall panels has been extensively investigated, limited studies focused on the seismic performance of multi-storey CFS strap-braced frames. Previous research highlighted that the presence of vertical loading can significantly reduce the lateral load and ductility capacity of strap-braced walls by amplifying the secondary moments due to P-Δ effects. While this effect is generally ignored in current design practice, it may lead to premature failures and poor seismic performance. This study aims to investigate the efficiency of a new design methodology to take into account the vertical load effects on the performance of multi-storey CFS strap-braced frames. Detailed experimentally validated FE models of CFS panels were developed in ABAQUS and used to obtain equivalent hysteretic models in OpenSees. The seismic performance of 6-storey strap-braced frames designed based on the Eurocode 8 and the proposed design methodology were then investigated under a set of artificial spectrum-compatible records. While the code-base design did not satisfy the ASCE/SEI 41–17 Life Safety (LS) and Collapse Prevention (CP) ductility limits, all performance targets were met using the proposed design methodology. The results of Incremental Dynamic Analyses (IDA) also indicated that meeting the code capacity requirements could not prevent extensive global damage in the strap-braced frames, due to soft-storey failure modes associated with the premature buckling of chord studs. Finally, the efficiency of the proposed design compared to its code-compliant counterpart was demonstrated under a set of 20 real spectrum compatible records, showing higher ductility capacity and considerably lower damage levels.

Fragility analysis and inelastic seismic performance of steel braced-core-tube frame outrigger tall buildings with passive adaptive negative stiffness damped outrigger

This paper investigated the fragility and inelastic performance of steel braced-core-tube frame outrigger (SBFO) tall buildings with passive adaptive negative stiffness damped outrigger (A-NSDO) systems. The proposed A-NSDO provided passive negative stiffness to achieve substantial damping effect for tall buildings at elastic stage. Once tall buildings was subjected to excessive earthquakes and yielded, the A-NSDO was capable of stiffening the connection between outrigger ends and perimeter columns passively and adaptively to guarantee the integrity of tall buildings. Passive configuration and working mechanism of the A-NSDO were introduced and then its adaptive behavior was validated through experiments. Based on the results of incremental dynamic analysis, fragility analysis of two SBFO structures with different outrigger systems including conventional outrigger, conventional damped outrigger, and A-NSDO, was provided to evaluate structural vulnerability for different limit states like serviceable state, elastic state, plastic state, and collapse state. The inelastic performances SBFO tall buildings with different outrigger systems were discussed in detail, including seismic envelopes, time history results, response spectra, and hysteretic responses of columns, braces, and the A-NSDO. Numerical results validated that the proposed A-NSDO not only took its advantage at elastic states for SBFO tall buildings but was also beneficial during the inelastic states.

Improving semi-active vibration control of an 11-story structure with non-linear behavior and floating fuzzy logic algorithm

In recent years, vibration control of structures subjected to the wind, earthquakes and traffic loads has been broadly studied. Based on this, different types of dampers and control systems have been used and evaluated in the form of active, semi-active, passive, and hybrid control. In this study, to control the vibrations of an 11-story structure under the effect of seismic load, the semi-active control approach of structural vibrations is used, with the help of Magneto-Rheological, MR, damper and using fuzzy logic algorithm decision system. In addition to using fuzzy inference system to determine the appropriate control voltage of the MR damper, the floating fuzzy inference system is also used to improve the performance of control system. In other words, to improve the performance of the fuzzy system with fixed membership functions, floating fuzzy system has been used with variable range for membership functions. The proposed fuzzy system is implemented in two different decision states; first, making decision based on velocity and second, making decision based on the velocity and displacement. Implementation of fuzzy inference system is conducted in MATLAB, and linear and nonlinear structural model in OpenSEES, where TCP/IP connection between them is used. The results of incremental dynamic analysis with maximum acceleration of 0.1 g to 1.0 g with incremental step of 0.1 g indicate that using floating fuzzy control system for decision based on velocity reduces the average displacement of the roof about 17.6% in linear structure and 22% in nonlinear structure, while in decision making based on velocity and displacement, these values are about 1.3% and 1.34% in linear and nonlinear structures, respectively.

Factor mapping method for grouped input variables and its application to seismic damage analysis

The study considers the characterization of global seismic damage indices of randomly parametered inelastic structures with a view to estimate the relative importance of underlying random variables with respect to variability in these damage indices. We build on an existing simulation-based approach, namely, the factor mapping method, to tackle the problem. Here, an ensemble of input variables is classified into two categories, depending upon whether a sample vector produces a global response damage measure in a pre-defined interval or not. We propose that a measure of distance between samples in these two categories be established in terms of an estimate of the Bhattacharyya distance. This distance is taken to measure the relative importance of individual/groups of input variables with respect to the damage index of interest. Illustrations include results of incremental dynamic analysis of a randomly parametered four-storied inelastic frame under a suite of scaled recorded ground motions.

Seismic fragility of legged liquid storage tanks based on soil type classifications

Recent earthquakes around the world have caused extensive damage or the complete collapse of legged storage tanks. The damage typically observed includes local buckling in the upper zone of the tank legs and anchor failures and indicates that legged storage tanks are highly vulnerable structures. Although the seismic response of legged storage tanks is affected by structural and hydrodynamic properties, the soil type where the tank is constructed can significantly influence the seismic response of these structures. However, the influence of soil type on the seismic fragility of legged tank structures has been not been extensively studied. In this investigation, the influence of soil type classification on the seismic fragility of legged wine storage tanks is evaluated by comparing the fragility curves of a typical legged storage tank, considering different soil types and different plate thicknesses for the tank legs. A mathematical model capable of capturing the most common failure modes observed was developed and used to generate fragility curves from results of incremental dynamic analyses with the ground motion records grouped by soil type. The fragility curves showed that the probability of failure of the legged storage tanks were highly dependent on the soil type on which the tank was located. Recommended thicknesses of the tank legs according to the soil type, seismic zone and the probability of failure are presented.

Proposed time-dependent approach to seismic loss evaluation through the life cycle of a structure

In this paper, an efficient time-dependent approach to seismic loss evaluation is proposed to calculate the probability distribution function of the life cycle cost of a structure. In the current literature, the evaluation of seismic loss has almost exclusively focused on estimating the mean value of the life cycle cost which does not include the information about the full extent of seismic loss variability. The proposed method aims to employ the FEMA-P-58 approach in evaluating the probabilistic distribution of total seismic repair cost in the life cycle of a structure. This method also considers the effect of time-dependent phenomena on loss evaluation while it keeps the required computational effort at an affordable level. A Monte Carlo sampling technique is applied to consider all sources of uncertainties. In this approach, the appropriate response distribution of the structure is extracted from the incremental dynamic analysis results, and there is no need to repeat complex dynamic analysis calculations in each realization. To better demonstrate the proposed method, the life cycle cost of a 5-story steel special moment frame is investigated with various assumptions on its time-dependent specifications such as the monetary discounting effects, the influence of different discount rates and building depreciation over time.

Reduction of seismic resiliency of RC structures caused by chloride corrosion for typical school buildings located in hot climates

The performance of Reinforced Concrete (RC) structures, as one of the most widely used structures in civil engineering, during its useful life is always affected by various deterioration factors such as chloride corrosion, and can lead to irreparable financial and human losses. Therefore, in this study, the effects of chloride corrosion on the seismic resilience index of reinforced concrete structures as a criterion for comparing the amount of damage at different levels of seismic hazard have been investigated. In pursuit of this goal, a two-dimensional model of an elementary school located in Iran has been built in OpenSees software. The effects of chloride corrosion have been applied in two time periods of 15 and 30 years after starting its related process. This corrosion would emerge in the form of uniform reduction of the reinforcement bars diameter of the columns and shear walls as well as the reduction of compressive strength of the concrete cover and steel yield stress to the structure. Fragility and vulnerability curves associated with the structural and non-structural elements were traced using the obtained results of Incremental Dynamic Analysis (IDA) under the effect of eight processed strong ground motion records. Finally, the seismic resilience index of the structure is obtained at two hazard levels containing 10% and 2% in 50 years, assuming a linear recovery function for non-corrosion and corrosion conditions. At the end of this research, sensitivity analysis is conducted to explore the effects of damage index on the resiliency of the case study. The results of this study show that the existence of chloride corrosion in all cases has led to an increase in delay and recovery time and a decrease in the seismic resilience index of the structure. The influence of chloride corrosion on the resiliency of vital structures highlights the urgent need for taking corrosion issues into consideration of engineers and stakeholders to enhance the resiliency and reduce the vulnerability of structures during coming natural hazards such as earthquakes and floods.

Seismic Response Modification Factors for Buildings Featuring a Gravity Transfer System by Incremental Dynamic Analyses

ABSTRACT Tall buildings featuring transfer structures are commonly constructed in lower seismicity regions. Discontinuities in load paths of structural systems in the building were found to compromise ductility of the building. In a force-based seismic design procedure, response modification (R) factor is uncertain to cater for the undesirable features. This article presents a methodical approach for evaluating the seismic performance of such buildings. Results of incremental dynamic analyses of case study buildings indicated a high R-factor, due to the inherent over-strength. A local amplification factor (is recommended to account for localised shear at structural walls above the transfer floor level.

Seismic fragility and post-earthquake reparability of circular reinforced concrete bridge columns with low-bond high-strength reinforcements

Authors proposed to use low-bond high-strength reinforcement (LBHSR) as the longitudinal reinforcement of reinforced concrete (RC) columns to develop the self-centering RC engineering structures based on the experimental conclusions that the LBHSR minimized residual deformation of test columns because of the low-bond high-strength property. Because the structural form of the proposed RC column was simple and the technology was low-cost, author proposed to use this type of RC column to fabricate the bridge column system. Two bridge archetypes with single and double columns reinforced by LBHSRs and high-bond normal-strength reinforcements (HBNSRs) were designed for numerical analysis using OpenSees program. A modified Young’s modulus of steel rebar was used to simulate the steel-bond slip behavior of the proposed RC column with LBHSRs, and the comparison results proved the applicability of this method. Based on the proposed OpenSees element model, seismic fragility and post-earthquake reparability of the designed bridge archetypes with LBHSRs and HBNSRs were compared based on the incremental dynamic analysis results. It was found that the use of LBHSR could greatly improve the post-earthquake reparability and reduce the collapse probability of bridge archetypes. The equations of the FEMA and JRA codes (FEMA, 2009; Tarfan et al., 2019) were used to predict the residual lateral drifts of bridge archetypes, and the comparison results indicated that both codes much overestimated the residual lateral drifts.

Seismic reliability assessment of steel moment-resisting frames using Bayes estimators

The aim of this study was to develop an efficient probability-based seismic fragility assessment method for steel moment-resisting frames (MRFs). In this method, Bayes estimators are used to improve the accuracy of the results based on new analyses or experimental observations. The efficiency of Bayes estimators in the updating process of fragility curves is demonstrated based on the results of incremental dynamic analysis of three-, five- and seven-storey steel MRFs under a set of 40 spectrum-compatible earthquake ground motions. The results indicate that the constant-hazard-level (engineering demand parameter based) fragility analysis approach leads to less than 6% error in the prediction of performance levels and therefore can be considered a competent alternative to the more computationally expensive constant-performance (intensity measure based) approach. While the earthquake duration can considerably affect the results of fragility analysis, the prediction errors can be reduced to an acceptable level through selection of four different time intervals with at least three records in each group. It is also concluded that Bayes estimators can generally provide a very good level of accuracy in updating fragility curves by reducing the maximum errors to less than 2.5% compared with the exact values.