Shear Wall Buildings Research Articles

An Energy Dissipating Seismic Connector for Precast Concrete Shear Walls

In this study, several steel connector shapes were analytically evaluated as potential new seismic energy dissipating devices between vertical precast concrete shear wall panels. Based on the results of analytical and experimental studies, a multiple yield zone (MYZ) connector is proposed due to its improved performance (in energy dissipation) when compared to the conventional U-shaped flexure plate (UFP) device. Unlike the UFP, the MYZ connector provides stiffness and energy dissipation in both horizontal and vertical directions. The response of a shear wall building system utilizing the MYZ or UFP connectors was evaluated using a simplified frame model. The MYZ connector performed better than the UFP alternate both in terms of energy dissipation in the device and with respect to improved structure response. The use of multiple (distributed) yield zones through circular cut-outs is key in the performance enhancement observed with the MYZ connector.

EVALUATION OF SEISMIC PERFORMANCE ENHANCEMENT TECHNIQUES FOR SHEAR WALL BUILDINGS USING ADVANCED MATERIALS AND SYSTEMS

There has been constant deliberation regarding promising seismic performance enhancement techniques for the reinforced concrete (RC) high-rise structures built before adopting existing seismic design codes. The research reported in this paper focuses on advanced approaches for improving the seismic performance of the shear wall structural system using high-performance reinforced concrete jackets and an outrigger-bracing system consisting of braces with improved hysteresis response. Following the case study region’s seismicity and design criteria, inelastic analyses are conducted to evaluate the demand-to-capacity ratios of primary vertical structural members of a pre-code twenty-six-story building. With the application of the proposed retrofit approaches and their various configurations, the design inadequacy of several structural members is eradicated. After validating the adopted fiber-based discretizations of the retrofit techniques with recent experimental studies, detailed three-dimensional numerical models are developed for the high-rise structures. Inelastic pushover analyses and dynamic response simulations under a diverse set of earthquake ground motions with increasing intensity levels are conducted to capture the buildings’ seismic performance until failure. The probabilistic seismic performance assessment enabled selecting the most effective technique for enhancing the seismic performance of shear wall buildings while minimizing disruption to the building.

Energy Performance Analysis of Buildings in Terms of Alternative Reinforced Concrete Structural Systems

In this study, the thermal energy performances and environmental effects of two different reinforced concrete structures, Pure Shear Wall (PSW) Building and Shear Wall-Frame (SWF) Building, were investigated in the climatic conditions of Elazig province. Thermal performance analysis for both buildings; was carried out with the TS 825 program. First of all, through this program, monthly and annual heating loads were determined for 11 different alternative building component scenarios of two different buildings. Subsequently, efficiency alternatives were created in accordance with the climatic conditions of the region and TS 825. Efficiency alternatives designed for both buildings have been analyzed together with their completely uninsulated and current states. Finally, buildings with reinforced concrete carrier systems, energy analysis methods and efficiency alternatives were compared and evaluated based on the results of the analysis. As a result, it has been observed that the building with the PSW system consumes more energy than the building with the SWF system when it is uninsulated and in its current condition.

EVALUATION OF SEISMIC PERFORMANCE ENHANCEMENT TECHNIQUES FOR SHEAR WALL BUILDINGS USING ADVANCED MATERIALS AND SYSTEMS

There has been constant deliberation regarding promising seismic performance enhancement techniques for the reinforced concrete (RC) high-rise structures built before adopting existing seismic design codes. The research reported in this paper focuses on advanced approaches for improving the seismic performance of the shear wall structural system using high-performance reinforced concrete jackets and an outrigger-bracing system consisting of braces with improved hysteresis response. Following the case study region’s seismicity and design criteria, inelastic analyses are conducted to evaluate the demand-to-capacity ratios of primary vertical structural members of a pre-code twenty-six-story building. With the application of the proposed retrofit approaches and their various configurations, the design inadequacy of several structural members is eradicated. After validating the adopted fiber-based discretizations of the retrofit techniques with recent experimental studies, detailed three-dimensional numerical models are developed for the high-rise structures. Inelastic pushover analyses and dynamic response simulations under a diverse set of earthquake ground motions with increasing intensity levels are conducted to capture the buildings’ seismic performance until failure. The probabilistic seismic performance assessment enabled selecting the most effective technique for enhancing the seismic performance of shear wall buildings while minimizing disruption to the building.

Some Issues in the Seismic Assessment of Shear-Wall Buildings through Code-Compliant Dynamic Analyses

Due to their excellent seismic behavior, shear wall-type concrete buildings are very popular in earthquake-prone countries like Chile. According to current seismic regulations, the performance of such structures can be indifferently assessed through linear or non-linear methods of analysis. Although all the code-compliant approaches supposedly lead to a safe design, linear approaches may be in fact less precise for catching the actual seismic performance of ductile and dissipative structures, which can even result in unconservative design where comparatively stiff buildings like reinforced-concrete shear-wall (RC-SW) buildings are concerned. By referring to a mid-rise multistory RC-SW building built in Chile and designed according to the current seismic Chilean code, the paper investigates the effectiveness of the linear dynamic analyses to predict the seismic performance of such kind of structures. The findings show that the code-compliant linear approaches (Modal Response Spectrum Analysis and Linear Time-History Analysis) may significantly underestimate the displacement demand in RC-SW buildings. This is highlighted by the comparison with the results obtained from the Non-Linear Time-History Analysis, which is expected to give more realistic results. A set of ten spectrum-consistent Chilean earthquakes was considered to carry out the time-history analyses while a distributed-plasticity fiber-based approach was adopted to model the non-linear behavior of the considered building. The paper highlights how the risk of an unsafe design may become higher when reference is made to the Chilean code, the latter considering only the Modal Response Spectrum Analysis (MRSA) without even providing corrective factors to estimate the inelastic displacement demand. The paper checks the effectiveness of some amplifying factors taken from the literature with reference to the case-study shear-wall building, concluding that they are not effective enough. The paper also warns against the danger of local soft-story collapse mechanisms, which are typical of reinforced concrete frames but may also affect RC-SW buildings when weaker structural parts made by column-like walls are present at the ground floor.

Periods and Mode Shapes for Uniform Shear Wall Buildings: Importance of Selecting the Appropriate Dynamic Behavior

The distribution of seismic loading to each storey of a building depends on a number of factors, mainly on the periods, mode shapes and modal participation. The estimation of these dynamic characteristics is essential in analyzing the seismic response of multi-storey buildings. Based on a rigorous dynamic analytical model of the building, this research provides a novel database of vibration modes of multi-storey buildings with reinforced concrete (RC) shear walls. The Stodola–Vianello iterative method was used to determine these. The first modes of vibration, cumulating a modal mass participation ratio (MMPR) greater than 90%, are summarized and presented in a table form. The results are equally valid for uniform buildings with masonry infill walls. The research has highlighted that the eigenvectors are independent of the values of the mass and the mechanical characteristics of the structure (the modulus of elasticity, the moment of inertia and height) but also on the variation of these characteristics over the height of the building. Consequently, for shear wall buildings with identical storeys, the eigenvectors, the MMPRs and the modal participation factors are accurately determined for this type of structure. The significance of the research consists of providing a table that engineers and researchers can easily use to determine the dynamic characteristics of the building, thus avoiding repetition of the calculations relating to this type of buildings. The study has also highlighted the importance of selecting the appropriate dynamic behavior of the structure for seismic design.

A comparative study of seismic analysis, design, and collapse safety margins of tall buildings in the United States and Japan, Part I: Performance-based analysis and design

Performance-based seismic analysis and design of tall buildings have become increasingly common in the United States and have been the standard practice in Japan for a long time. The methodologies for seismic hazard analyses, selection of earthquake records for design, and acceptance criteria, however, are widely different in the two countries. Japan experiences large earthquakes and strong shakings of buildings significantly more frequently than the United States, and the data on actual seismic performance are richer in Japan than in the United States. Comparison of performance and calibration between the two design procedures can help to improve the quantitative assessment of seismic performance of buildings in the United States. This article presents the application of US and Japanese procedures to a tall building archetype once proportioned, analyzed, and designed according to US practices and once per Japanese practices. The structural systems selected are very different; for the United States, the archetype is designed using a core reinforced concrete shear wall building with composite floor systems and steel columns as the gravity system, whereas for Japan, the archetype is designed using a steel moment frame made of square concrete-filled steel tube (CFT) columns and composite beams and installed with oil dampers. Although the design procedures followed are vastly different, the seismic performances of the systems are rather similar during serviceability, design basis, and maximum considered events. As will be presented in the second part of this article, the collapse safety margins of the two designs are significantly different.

Seismic pounding damage to adjacent reinforced concrete frame–shear wall buildings and freestanding contents

AbstractClosely spaced tall buildings are common in modern urban areas due to limited supply of land to accommodate rapid growth of population. These buildings are vulnerable in seismically active regions particularly when earthquake‐induced pounding occurs between adjacent buildings, resulting in high floor acceleration spikes that may lead to excessive demands on building contents (BCs). This paper examines the effect of seismic pounding on damage to adjacent reinforced concrete (RC) frame–shear wall buildings and their freestanding contents using nonlinear response‐history analyses (RHA). A cascading analysis approach is adopted to obtain absolute floor accelerations of pounding tall buildings, which are then applied to determine response of freestanding contents dominated by either sliding or rocking motions. In order to provide a useful tool for practicing engineers and facilitate analyses, the buildings are simplified as story‐based multiple‐degree‐of‐freedom (MDOF) flexural‐shear models, and unanchored contents are idealized as single‐degree‐of‐freedom (SDOF) oscillators, all of which are approximated using OpenSees and verified against solutions to their exact equations of motion solved using Matlab. It is shown that seismic pounding leads to higher building damage and alters story damage distribution patterns. It is concluded that pounding significantly increases sliding potential and maximum sliding displacement demands on stocky contents, especially those on higher floors. The transitions of stick–slip response of the contents coincide well with pounding occurrences. It is also concluded that pounding has detrimental effects on slender rocking contents, but rocking rotation histories of these contents do not show abrupt changes upon impact.

An analytical framework to assess earthquake-induced downtime and model recovery of buildings

While modern seismic design codes intend to ensure life-safety in extreme earthquakes, policy-makers are moving toward performance objectives stated in terms of acceptable recovery times. This article describes a framework to probabilistically model the post-earthquake recovery of buildings and provide quantitative seismic performance measures, expressed in terms of downtime, that are useful for decision-making. Downtime estimates include the time for mobilizing resources after an earthquake and conduct necessary repairs. The proposed framework advances the well-established Federal Emergency Management Agency (FEMA) P-58 and Resilience-based Earthquake Design initiative (REDi) methodologies by modeling temporal building recovery trajectories to target recovery states, such as stability, shelter-in-place, reoccupancy, and functional recovery. The shelter-in-place recovery state accounts for relaxed post-earthquake habitability standards, in contrast with the reoccupancy recovery state that relates to pre-event habitability criteria. Analogous to safety-based codes, which specify a threshold for the probability of collapse under a given ground motion shaking intensity, this framework permits evaluating the probability of a building not achieving a target recovery state, for example, shelter-in-place, immediately after an earthquake, or, alternatively, the probability of achieving a target recovery state, for example, functional recovery, within a specified time frame. The proposed framework is implemented to evaluate a modern 12-story residential reinforced concrete shear wall building in Seattle, WA. The assessment results indicate that under a functional-level earthquake (roughly equivalent to ground motion shaking with a return period of 475 years), the probability of not achieving shelter-in-place immediately after the earthquake is 22%, and the probability of downtime to functional recovery exceeding 4 months is 88%, which far exceeds acceptable thresholds suggested in the 2015 National Earthquake Hazards Reductions Program (NEHRP) guidelines and FEMA P-2090.

Contemporary and Novel Hold-Down Solutions for Mass Timber Shear Walls

‘Mass timber’ engineered wood products in general, and cross-laminated timber in particular, are gaining popularity in residential, non-residential, as well as mid- and high-rise structural applications. These applications include lateral force-resisting systems, such as shear walls. The prospect of building larger and taller timber buildings creates structural design challenges; one of them being that lateral forces from wind and earthquakes are larger and create higher demands on the ‘hold-downs’ in shear wall buildings. These demands are multiple: strength to resist loads, lateral stiffness to minimize deflections and damage, as well as deformation compatibility to accommodate the desired system rocking behaviour during an earthquake. In this paper, contemporary and novel hold-down solutions for mass timber shear walls are presented and discussed, including recent research on internal-perforated steel plates fastened with self-drilling dowels, hyperelastic rubber pads with steel rods, and high-strength hold-downs with self-tapping screws.

Seismic performance of a high-rise building by using linear and nonlinear methods

In this paper, the seismic behavior of the existing reinforced concrete tall building is investigated by using the linear and nonlinear dynamic methods. The selected existing reinforced concrete structure was designed according to Turkey Seismic Code-2007. The performance analysis according to the Turkey Building Earthquake Code-2019 is realized in a 41-story reinforced concrete shear wall-framed structure in Istanbul where active fault lines are located. For high-rise building, firstly, spectrum analysis according to mode superposition methods of linear computational methods used within the scope of strength-based design is performed. Turkey Building Earthquake Code-2019 advises a nonlinear deformation-based design approach to determine more accurately the behavior of high-rise building, as in the earthquake regulations of other developed countries. In addition, the nonlinear time history analyses of building were performed. At the end of the study, torsional irregularity is seen on the normal floors and intermediate floor; stiffness irregularity was found on second floors. In addition, it has been observed in some of the oblique columns of the building that load bearing capacities were exceeded due to creep, axial compressive loads and severe damages occurred. According to the Turkey Building Earthquake Code-2019, the high-rise reinforced concrete shear wall building is not expected to satisfy life safety performance levels under design earthquake.

Resilience-Based Retrofitting of Adjacent Reinforced Concrete Frame–Shear Wall Buildings Integrated into a Common Isolation System

Adjacent buildings of three to five stories with small spaces between them are widely used as offices, schools, and hospital wards. The seismic resilience of such buildings is critical, and retrofitting adjacent buildings by integrating them into a common isolation system is considered effective. The resilience-based retrofitting of adjacent RC frame–shear wall buildings was investigated through a case study. First, the critical engineering demand parameters (EDPs) dominating the resilience performance of such buildings were identified. An isolation scheme was designed to improve their seismic resilience, emphasizing control effect of seismic isolation on critical EDPs. The effect of the yield ratio of the isolation system on the seismic resilience of retrofitted buildings was investigated by comparing three cases. A yield ratio of 2.5% is preliminarily recommended as a valuable reference for the resilience-based retrofitting of adjacent RC frame–shear wall buildings.

Experimental investigation on the effect of openings on the in-plane shear strength and stiffness of cross-laminated timber panels

The high in-plane shear strengths of cross-laminated timber (CLT) make it a good candidate for use as shear walls in buildings in areas of high seismicity such as Japan. One important aspect of CLT walls, and one that is presently poorly understood, is the influence of openings on the in-plane shear carrying capacity. The main purpose of this paper is to experimentally evaluate the effect of openings on the in-plane strength and stiffness of CLT panels with openings. In this study, 24 CLT panels were tested using a diagonal compression test configuration. In particular, they were three identical replicates of eight CLT panels. One of these eight panels was a solid panel, while the other seven panels had openings with different sizes and aspect ratios. The results showed that the panels with openings with the same area but different aspect ratios had different failure directions and reduction factors for panel shear strength and stiffness. Panels with rectangular openings with different orientations relative to the panel’s major and minor shear direction had different failure direction and reduction factors. In addition, the effect of openings on the reduction of initial stiffness for CLT panels was found to be greater than their effect on the reduction of shear strength. This paper's findings will help clarify the reduction in strength and stiffness of CLT panels with openings, which is an important aspect of the seismic design of buildings.

Computational modelling of dynamic soil-structure interaction in shear wall buildings with basements in medium stiffness sandy soils using a subdomain spectral element approach calibrated by micro-vibrations

This paper presents a strategy for modelling dynamic soil-structure interaction (DSSI) using the spectral element method (SEM) with a Discontinuous Galerkin approach, calibrated by micro-vibrations. The proposed methodology allows not only to adjust the vibration frequencies of the structure but also the observed vibration modes. First, models of two structural shear wall buildings with basements in medium dense sandy soils are developed to estimate empirical modal characteristics and calibrate the structural subdomain and low-strain site properties. Convenient 3D arrays of multiple seismic sensors are used to obtain the environmental vibrations measurements. Afterwards, an optimization process is conducted to calibrate volumetric models of structures. This optimization is performed by preserving the most relevant modal frequencies and shapes to achieve an equivalent dynamic response. Finally, structural models are placed into a neighbouring soil model (soil subdomain), approximating nonlinear soil behaviour by an equivalent linear strategy. Using this complete soil-structure interaction model, relevant engineering performance parameters are assessed via simulations of buildings subjected to a plane wave excitation. The results show the significant effect DSSI have in shear-wall buildings with basements and the importance of considering the flexibility of the foundation in the interpretation of the results. In general, results indicate that DSSI effects are strongly dependent on the input frequency content, which might cause a reduction of the inter-story drifts. Furthermore, a significant period lengthening of the studied structures up to 47% is found, as well as a considerable decrease in story shear up to 220% and a maximum lateral roof displacement reduction of 34% when compared against fixed base referential responses.

Analysis of Soft Story Building with Different Percentages of Shear Walls by Using ETABS Software

Abstract: In late decades, shear walls and tube structures are the most proper basic structures, which have made the stature of solid structures be taken off. In this way, ongoing RC tall structures would have more confounded auxiliary conduct than previously. Here in this paper; we will examine the auxiliary parts of one of the tallest RC structures, situated in Hyderabad seismic zone, with 15 stories where shear wall framework with sporadic openings are used under both horizontal and gravity stacks, Because of utilitarian necessities, for example, entryways, windows, and different openings, a shear wall in building contains numerous openings. The size and area of openings may fluctuate for building and utilitarian perspective. Hence this examination is done on 15 story outline wall building utilizing Response range investigation by utilizing ETABS V 9.7.4. The models are examined with increment in level of shear mass of 15%, 18%, 28% through and through story. Keywords: Structural forms, Irregular openings, Drift, Shear, and Moments

Quantitative evaluation and improvement of seismic resilience of a tall frame shear wall structure

SummaryTall buildings are an important part of a city, and their earthquake‐induced damage or collapse will lead to heavy losses, extended repair time, and casualties. Therefore, it is essential to quantify and improve the resilience of tall buildings. To this end, this paper develops a component damage‐based metric to characterize tall buildings' functionality loss and then proposes a general quantitative evaluation process to evaluate tall buildings' resilience. Next, the evaluation process is applied to a 42‐story reinforced concrete frame shear wall building to demonstrate its applicability. Finally, retrofit strategies on nonstructural components are discussed to enhance the building's resilience. It can be concluded that the proposed metric can be effectively used to evaluate tall buildings' functionality loss. The building being studied has great seismic resilience, with resilience values of 99.95%, 98.68%, and 88.69% at service level earthquake (SLE), design level earthquake (DBE), and maximum considered earthquake (MCE), respectively. The influence of nonstructural components on seismic resilience is greater than that of structural components at SLE and DBE levels. It is an effective alternative to enhance the seismic resilience of tall buildings under SLE and DBE by improving the performance of partition walls, ceilings, and equipment.

Modified Damage Index Calculation Method for Frame-Shear Wall Building Considering Multiple Demand Parameters

In this study, multiple objectives on earthquake damage assessment procedures have been investigated. The Unified performance-based design (UPBD) method was primarily used to design the Reinforced Concrete (RC) frame shear wall building. The nonlinear dynamic analysis is performed considering spectrum compatible ground motions (SCGM) as per EC-8 demand spectrum at 0.45g level and type B soil condition. It estimated the Damage index (DI) of the building by using Park and Ang method. This method is highly time-consuming as the storey height increases. Hence, it is not suitable for large scale investigation. Therefore, a new approach has been suggested to reduce the computational time and efforts in the case of complex structures to evaluate the global damage index (GDI). In this present study, the most three influencing parameters of the building has been considered to find the global damage index (GDI). And it has also been observed that the most damage occurs on the ground storey of the building compared to the remaining floors. The suggested method efficiently calculates a reliable GDI that can assess building damage from small to large scale.

Probabilistic seismic resilience quantification of a reinforced masonry shear wall system with boundary elements under bi-directional horizontal excitations

The concept of resilience is gaining increased attention in disaster management due to the recent awareness of the need to reduce the detrimental post-event effects of natural disasters, e.g., earthquakes. Resilience is a practical concept that includes pre-event (preparedness and mitigation) and post-event (response and recovery) activities. Quantitative resilience assessment approaches are needed to compare the available mitigation strategies to decide on the most suitable strategy and provide better support for decision-making procedures. In this study, a methodology for quantifying the seismic resilience of reinforced masonry shear wall (RMSW) buildings with end-confined masonry boundary elements is implemented. The uncertainties associated with structural and non-structural losses and estimated recovery time uncertainties are considered while quantifying the resilience index of RMSW buildings. The archetype buildings studied have 8-, 10-, and 12-storey heights and are located in Vancouver, representing a high seismic zone in Canada. First, a numerical model was developed using OpenSees to derive the fragility surface for the studied archetypes subjected to bi-directional horizontal excitation. Second, a Monte Carlo simulation was performed to quantify the resilience index of each archetype considering the above-mentioned uncertainties. The results prove the robustness of ductile RMSW buildings having end-confined MBEs in mitigating the losses associated with disaster events. Additionally, the findings provide comprehensive and valuable information for earthquake mitigation measures and disaster risk reduction programmes.

Topographical and structure-soil-structure interaction effects on dynamic behavior of shear-wall buildings on coastal scarp

This paper investigates numerically the influence of slope topography, soil stratigraphy and dynamic interaction between close shear-wall buildings of typical residential projects on coastal scarp. A numerical model based on real buildings taken as cases for this study, is calibrated with field measurements. A nonlinear finite element dynamic analysis is conducted to derive topographical aggravation factors prior to excavation and construction of the buildings and to assess structural responses after their construction for different interaction scenarios and ground motion inputs. We concluded that the surface profile has a large effect on the dynamic response of a stiff low-rise building when their characteristic wavelengths are close each other and it can play a detrimental role increasing up to 80% the interstory drift, 35% the seismic coefficient and 57% the fixed-base fundamental period depending on the input. In several other input cases including far-field earthquake records, dynamic soil-structure interaction is beneficial. Furthermore, it is shown that the structure-soil-structure scenario has negligible additional effect from a practical point of view with respect to soil-structure interaction for this case of study. These results suggest that similar residential projects should be cautious in the design of low-rise buildings located near a slope crest.

Effects of the Georgia Sedimentary Basin on the Response of Modern Tall RC Shear-Wall Buildings to M9 Cascadia Subduction Zone Earthquakes

Tall residential RC shear wall buildings (RCSW), which are predominant in Metro Vancouver, have the potential to experience large magnitude earthquakes generated by the Cascadia Subduction Zone (CSZ). Furthermore, the region lies above the Georgia sedimentary basin, which can amplify the intensity of ground motions at medium to long periods and the resulting damage in tall structures. This study provides insights into the effects of the Georgia sedimentary basin amplification on (1) spectral accelerations associated with magnitude 9 (M9) CSZ earthquakes, (2) resulting force- and deformation-controlled actions in modern tall RCSW buildings, and (3) ensuing earthquake-induced repair costs and times. To this end, we leveraged a suite of physics-based ground motion simulations of a range of M9 CSZ earthquake scenarios, which explicitly consider basin effects, and benchmarked these scenarios against a range of seismic hazard intensities, which neglects basin effects. While the M9 simulations have an estimated 500-year return period, at deep basin sites their spectra exceed the 2,475-year hazard in the 1–3 s period range. Nonlinear dynamic analysis results under probabilistic seismic hazard estimates result in negligible collapse risk. In contrast, collapse risk conditioned on the occurrence of the M9 motions results in probabilities as high as 15%. Additionally, seismic demands from the M9 simulations at deep basin sites result in earthquake-induced repair costs and times that exceed those associated with the 2,475-year hazard level.