Reinforced Concrete Frame Buildings Research Articles

Fire scenario-based damage assessment of ductile reinforced concrete buildings using computational fluid dynamics models

This study aims to develop a computational fluid dynamics (CFD)-based framework to assess the thermal behavior of reinforced concrete (RC) structures with non-uniformly distributed fire damage. To achieve this, a CFD model that can predict fire-induced temperature was validated using experimental data of an RC column specimen obtained from an existing study. It was then extended to develop the CFD model of an RC building frame to investigate the extent and pattern of damage to its columns and beams under various fire scenarios, combinations of fire intensity, ventilation coefficient, and fire source locations. The non-uniform temperature distributions of the columns and beams were used to modify the stress–strain curve of concrete and rebar and to perform a moment–curvature analysis to evaluate their residual flexural strength. The computed flexural strengths were compared with those obtained from existing design guidelines. The guidelines were determined to be extremely cautious compared to the results of the proposed method.

The Effect of Soil Liquefaction and Lateral Spreading to the Seismic Vulnerability of RC Frame Buildings Considering SSI

ABSTRACT Evidence of past earthquakes highlighted the seismic vulnerability to buildings due to soil liquefaction and lateral spreading phenomena. Damage to buildings on a liquefiable site, especially on a gently sloping site, can be severe. The liquefied soil can undergo permanent lateral ground displacements as large as several meters in some cases, which can be severely disastrous to buildings. Recent physical tests and effective stress analyses of nonlinear dynamic soil-structure interaction (SSI) proved that simplified empirical processes are often improper for evaluating liquefaction-induced building settlements. A better understanding of the SSI effects is also essential in cases where the underlying soil is susceptible to liquefaction. In this respect, the interaction of the earthquake excitation and ground failure (i.e. soil liquefaction and lateral spreading) for buildings considering SSI is investigated herein. Typical low-code reinforced concrete (RC) frame buildings of different heights with shallow spread footings on liquefiable level-ground or sloping soils subjected to ground shaking are considered. The direct SSI approach is implemented. Predictive relationships are established between the maximum normalized differential displacements (horizontal or settlement) and the permanent ground displacement (PGD) vector at the level of foundation for low-code RC frame buildings with shallow spread footings on soils with high liquefaction potential subjected to ground shaking. Finally, vulnerability is expressed in terms of fragility and vulnerability curves as well as in terms of fragility surfaces as a function of two intensity measures.

Framework to assess the seismic performance of non-engineered masonry infilled RC frame buildings accounting for material uncertainty

Non-engineered construction accounts for more than half of the building stock in low and middle-income countries. A significant portion of these buildings is constructed using masonry infilled reinforced concrete (RC) frames with inadequate seismic detailing. This type of construction is prone to high levels of variability in the material properties, posing a significant challenge in their seismic performance evaluation. This research proposes a framework to assess the seismic performance of non-engineered constructed masonry infilled RC frame buildings, which considers the material uncertainty. A four-stage procedure based on Monte Carlo simulations is introduced, wherein engineering demand parameters and seismic performance are expressed in terms of probability distributions. The framework is demonstrated using a non-engineered housing archetype located in Sincelejo, Colombia. The results showed that the framework allows capturing the uncertainty in the materials construction variability of non-engineered houses. The results also showed that mean values of material properties may lead to significant errors in the seismic performance assessment of non-engineered constructed masonry infilled RC frames. The differences between the predicted minimum and maximum exceedance probabilities of a damage state can be greater than 80%.

Predicting the Influence of Soil–Structure Interaction on Seismic Responses of Reinforced Concrete Frame Buildings Using Convolutional Neural Network

Most regional seismic damage assessment (RSDA) methods are based on the rigid-base assumption to ensure evaluating efficiency, while these practices introduce factual errors due to neglecting the soil–structure interaction (SSI). Predicting the influence of the SSI on seismic responses of regionwide structure portfolios remains a challenging undertaking, as it requires developing numerous high-fidelity, integrated models to capture the dynamic interplay and uncertainties in structures, foundations, and supporting soils. This study develops a one-dimensional convolutional neural network (1D-CNN) model to efficiently predict to what degree considering the SSI would change the inter-story drifts and base shear forces of RC frame buildings. An experimentally validated finite element model is developed to simulate the nonlinear seismic behavior of the building-foundation–soil system. Subsequently, a database comprising input data (i.e., structural and soil parameters, ground motions) and output predictors (i.e., changes in story drift and base shear) is constructed by simulating 1380 pairs of fixed-base versus soil-supported structures under earthquake loading. This large-scale dataset is used to train, test, and identify the optimal hyperparameters for the 1D-CNN model to quantify the demand differences in inter-story drifts and base shears due to the SSI. Results indicate the 1D-CNN model has a superior performance, and the absolute prediction errors of the SSI influence coefficients for the maximum base shear and inter-story drift are within 9.3% and 11.7% for 80% of cases in the testing set. The deep learning model can be conveniently applied to enhance the accuracy of the RSDA of RC buildings by updating their seismic responses where no SSI is considered.

The influence of earthquake characteristics on the seismic performance of reinforced concrete buildings in Australia with varying heights

In Australia, most of the existing buildings were designed before the release of the Australian standard for earthquake actions in 2007. Therefore, many existing buildings in Australia lack adequate seismic design, and their seismic performance must be assessed. The recent earthquake that struck Mansfield, Victoria near Melbourne elevated the need to produce fragility curves for existing reinforced concrete (RC) buildings in Australia. Fragility curves are frequently utilized to assess buildings’ seismic performance and it is defined as the demand probability surpassing capacity at a given intensity level. Numerous factors can influence the results of the fragility assessment of RC buildings. Among the most important factors that can affect the performance-based seismic assessment of buildings are the building height and the characteristics of the earthquake. Despite this, very few studies accounted for the earthquake characteristics and the influence of height on the vulnerability of buildings in Australia. Consequently, the combined effect of building height and the characteristics of the earthquake were investigated in this study. This was achieved through numerical modeling and time-history analyses of three typical two-, four-, and nine-story RC frame buildings in Australia. Moreover, these buildings were subjected to three different types of ground motions which were: short- and long-duration, and near-fault earthquakes. Fragility analysis was then conducted for the three buildings under all the selected earthquake suites. It was noted from the median values of the fragility curves that the four-story and the nine-story RC buildings were 17% and 18% more susceptible to damage in comparison with the two-story building under short-duration earthquakes. Moreover, it was also noted that the median value of the vulnerability increased by 33%, 40%, and 50% for the two-, four-, and nine-story buildings, sequentially, when subjected to near-fault compared to short-duration earthquakes.

Seismic Capacity Estimation for Composite Multi-storeyed RC buildings

Seismic hazard happens to be one of the most devastative natural hazards to be faced by mankind. In view of urbanization and knowledge gained from past natural hazards, several urban cities have seen a transformation in building their habitats. These range from regular, irregular multistoried Reinforced Concrete (RC) buildings to several composite multi storeyed RC buildings due to certain inherent functional benefits (viz., ventilation, parking space, ease of construction etc.,). The existing seismic code regulations provided by BIS (Bureau of Indian Standards) do not specify any approach to arrive at appropriate design seismic forces and capacity for composite multi storeyed buildings. Therefore, it is imminent to assess the structural behaviour of these multistoried composite RC buildings under earthquake forces at the site location to provide a safe and functional configuration. Hence an attempt has been made in this study to analytically compare regular and composite RC building models having similar Plan and Height. The multistoried RC building configurations considered in this study comprises of regular RC building as well as RC building frame coupled with steel joists at certain locations to represent a composite structural system. These models are further analyzed to arrive at inherent nonlinear seismic capacity, ductility and design seismic forces necessary to be considered during design of RC building structure. Hence, a typical hypothetical G+5 regular and composite multistoried buildings were modelled and analysed using the nonlinear static (pushover analysis) approach. The outcomes of these analyses clearly portrays the variation in dynamic characteristics of the building frames represented in terms of its time period, inelastic capacity and response reduction factor (R). Moreover, the present study emphasizes to analytically evaluate the design seismic forces necessary for earthquake resistant design of composite buildings in any urban environment albeit the changes in structural configurations.

Seismic Vulnerability of Code Compliant RC Frame Building with Unreinforced Masonry Infill Walls

Unreinforced masonry (URM) infill walls in Reinforced concrete (RC) buildings are normally designed as non-structural elements. However, in the past, the post-earthquake response of the RC frame building showed that URM infill walls increase the strength and stiffness of the RC frame buildings. Further, it is also observed that URM helped to prevent the disastrous destruction by acting as a structural member in RC frame. In the present study, the performance assessment of a four-storey URM infill RC frame with different infill configurations, namely bare and Open Ground Storey (OGS) is done using fragility analyses. Nonlinear masonry material is modelled as the equitant three strut model in ETABS. Nonlinear static pushover analysis is applied for the analysis of the configured RC frames. The probability of damage states is determined by firstly converting pushover curves into capacity curves and accordingly, performance-point values of Spectral acceleration and Spectral displacement for seismic demand Zone-V (Elastic Response Spectra as per IS 1893:2016) using the capacity-spectrum method (ATC-40) are determined. The fragility function used is an approximation of the continuous to discrete distribution. Fragility curves and mean damage matrix are derived to compare performance with each other. From the vulnerability analyses, it is observed that the OGS framed RC building performs better as compared to the bare frame.

Influence of Structural Parameters on the Buckling of Longitudinal Steel Bar in RC Structural Wall

Reinforced Concrete (RC) structural wall is widely used in multistoried RC frame buildings to enhance lateral stiffness and lateral strength for earthquake resistance. One of the possible failure modes, observed during strong earthquake shaking, is the buckling of longitudinal steel reinforcement in the boundary elements of the wall. This also assumes importance in establishing damage states for seismic fragility analysis of RC wall. Although a few past studies have focussed on longitudinal bar buckling in RC members, detailed parametric study is absent particularly for such instability of bars in the boundary elements of the wall. In the present study, displacement-controlled nonlinear static analysis of several wall specimens is carried out using fibre-discretization of cross-section and distributed plasticity modelling in OpenSEES. Here, 27 different models of the isolated slender wall are created considering variations in six structural parameters, namely (a) length ratio of the boundary element to the wall, (b) axial force ratio, ratios of (c) longitudinal steel in web, and (d) transverse steel and (e) longitudinal steel in the boundary elements. The effect of wall thickness is accounted for through variation in axial force ratio. Using the analytical results from the nonlinear analysis of the wall models, the trends in drift ratio at the onset of longitudinal bar buckling damage states as functions of various key structural wall properties, has been investigated.

Accuracy of Seismic Response Evaluation of Two-Dimensional Analysis Model with Rigid Joints for RC Frame Buildings.

Three- or two-dimensional (2D) numerical models are used for the evaluation of the seismic performance of reinforced concrete (RC) buildings. This study examines a 2D numerical model for a specimen used in a full-scale four-story RC shaking-table test and evaluates the accuracy of the seismic response of the 2D numerical model, which is composed of a square fiber section model for the columns, a T-shape fiber section model for the beam and slab, and a rigid joint model for the beam-column joint. A parametric analysis of the effective slab width is performed to analyze its effects on the modal shape and natural period. The results suggest that the primary natural period of the considered model is almost identical to that associated with the experimental results. The applicability of the 2D numerical model for estimating the seismic response of the structure is established. By comparing the results of the seismic analysis and the experiment in the 50% amplitude of the JMA-Kobe wave, which corresponds to slightly exceeding VII on the modified Mercalli intensity scale, the root-mean-square percentage error of the 2D numerical model is 1.03% for the floor acceleration and 4.7% for the inter-story drift. Thus, the analytical model used in this study has sufficient accuracy in evaluating the seismic performance of buildings constructed in regions with a maximum seismic intensity of VII.

Dynamic behavior and retrofitting of RC frame building under vehicular bomb explosion

Although the terrorist explosion attacks on critical buildings caused by the Vehicle-Borne Improvised Explosive Device (VBIED) are low-probability events, the blast-induced progressive collapse of buildings generally lead to the catastrophic consequences of the events. Through the high-fidelity hybrid finite element (FE) model and numerical simulations, this work aims to get a deep insight into the progressive collapse behavior of high-rise reinforced concrete (RC) frame buildings under blast loadings induced by VBIED, as well as the feasibility of two blast-resistant external retrofitting measures, i.e., fiber reinforced polymer (FRP) and steel plate (SP). Firstly, the applicability of the hybrid FE modelling approach, element types and size, material models and parameters, as well as numerical algorithms, i.e., multi-material Arbitrary Lagrangian-Eulerian (MM-ALE) and Fluid-Structure Interaction (FSI), are fully validated by comparing with the explosion tests on 1/4-scale bare and prototype FRP/SP-retrofitted RC frame structures, respectively. Then, a twelve-story RC frame building is designed following the Chinese regulations, and the corresponding hybrid FE model is established. The failure modes and progressive collapse process of building under the explosions of cargo vans bomb (equivalent TNT of 1814 kg) specified by Federal Emergency Management Agency are numerically examined. Furthermore, the effectiveness of FRP/SP-retrofitted frame columns is assessed quantitatively. It derives that, the SP-retrofitted building is not collapsed for both the scaled distance of 1.0 and 0.55 m/kg1/3; by retrofitting FRP warps, the collapse of entire buildings can be prevented with the scaled distance of 1.0 m/kg1/3, while the progressive collapse of the retrofitted building occurs with a scaled distance of 0.55 m/kg1/3. The present work could provide helpful references for the blast-resistant evaluation, design and retrofitting of the as- and newly-built RC building structures.

Progressive collapse fragility of substandard and earthquake-resistant precast RC buildings

Several natural and man-made disasters have highlighted that precast reinforced concrete (RC) buildings often have insufficient levels of structural robustness, which is the last line of defence under extreme events. Even though robustness studies were originated by the progressive collapse of the Ronan Point precast RC building in 1968, such a structural feature of disaster resilience has been partially investigated in case of precast RC buildings to date. In this study, a precast RC frame structure representative of low-rise commercial buildings is analysed under different column loss scenarios, which can produce the partial or total collapse of the structural system. Two building classes are considered, namely, buildings designed only to gravity loads and buildings designed for earthquake resistance. Structural robustness is probabilistically assessed through a fragility analysis procedure, using three-dimensional fibre-based finite element models with nonlinear links simulating connections, large-displacement incremental dynamic analysis, and multiple performance limit states for damage assessment. The output of the study is threefold: (i) a detailed assessment of the effects of column loss on precast RC frame buildings, quantifying the major role of structural detailing and beam-column connections; (ii) a fragility-informed evaluation of beneficial effects of seismic detailing on structural robustness, which can drive designers in retrofitting of existing precast RC buildings and decision-makers towards prioritization-related issues; and (iii) the generation of typological fragility curves for progressive collapse risk assessment in both single- and multi-hazard environments. Progressive collapse fragility curves can be convolved with more classical fragility models describing the failure of single components (under, e.g., flow-type landslide impact, vehicle collision or blast) and hazard, to assess systemic structural risk.

Experimental Evaluation of Steel Bracings and Metallic Yield Damper as Retrofit Techniques for Severely Damaged RC Building Frames

ABSTRACT The concentrically placed hollow circular steel bracings and hybrid metallic yield dampers as structural retrofitting techniques for severely damaged reinforced concrete (RC) portal frames are evaluated under reverse-cyclic load conditions. In addition, the efficiency of a specially designed coupler-box assembly to retrofit severely damaged columns of the model frame by reconnecting the buckled or ruptured longitudinal reinforcing bars at the plastic hinge locations is evaluated under similar load conditions. Competency of the proposed techniques is assessed by comparing the hysteresis behavior, performance index parameters, and failure mechanism of the retrofitted frames with the native-tested conventional bare frame. The lateral load and deformation capacities are significantly enhanced in the retrofitted frames with a comprehensive increase of 2.0 times in the braced frame and 2.5 times in the damper-equipped frame compared to the conventional bare frame. A stable and symmetric post-yield behavior is noticed in the retrofitted frames until a lateral drift of 3.5% and 6% in braced and damper-fit frames, respectively, which is even higher than the collapse prevention drift level specified in FEMA codal guidelines.

Influence of BRBs deformation capacity on the seismic performance of RC building frames

The deformation design requirements of buckling-restrained brace (BRB) are explicitly stipulated in design standards to ensure the safety of the building structures. However, BRBs still have the risk of failure when the building structures are subjected to an extremely rare earthquake event. This investigation gives an insight into the seismic and collapse performance of BRB braced reinforced concrete (RC) frame structures considering the ultimate deformation capacity of BRBs. Three case study buildings of 3-, 6-, and 9-story RC frames equipped with BRBs that possess various ultimate deformation capacities are designed in accordance with Chinese standards. First, the significance of considering BRB failure in seismic performance evaluation is illustrated through comparative analysis. Then, the static pushover analysis and incremental dynamic analysis are conducted on BRB frames to quantitatively evaluate the influence of BRB ultimate deformation capacity on the seismic and collapse performance. The results reveal that the BRB ultimate deformation capacity has a significant influence on seismic response and collapse mode, especially under extremely rare earthquake events, and shall be legitimately considered in numerical modeling for accurate seismic performance evaluation. The BRB with an ultimate deformation safety coefficient of 1.2 will provide sufficient redundancy to ensure the safety of the building structures from BRB failure and potential collapse risk.

Rapid seismic response prediction of RC frames based on deep learning and limited building information

Building portfolio is the important urban engineering system, and the seismic resilience assessment of a city needs the quick and accurate prediction of the seismic responses of existed buildings. However, many existed buildings generally possess the problem that the design information materials are incomplete or completely lost. The major challenge in the seismic resilience assessment of building portfolio is how to predict the seismic responses of buildings quickly and accurately just using limited building information. This manuscript aims to develop a method for the seismic response prediction of the existed reinforced concrete (RC) frame buildings just using limited building information. A total of 162 typical RC frame buildings of low to medium rise are designed, and the inter-story drift (IDR) as well as peak floor acceleration (PFA) of each floor in each building are computed for 200 ground motions with nonlinear time history analysis (NLTHA) method. A convolutional neural network (CNN) is developed with ground motion records and five easy-getting building parameters as inputs. The outputs are IDR and PFA of each floor for the given building. Considering the physical means of an input parameter—number of stories, the modified loss function and modified evaluation function are proposed. The developed network is trained with the computed dataset and the modified loss function, and the trained model (referred to StruNet) can take the characteristics of ground motions and structures into consideration together comparing to previous studies. The proposed model is verified through four cases (i.e., 4 actual buildings with different construction time, occupancy types, and plane layouts), which are independent of the deep learning dataset. The results confirm that the proposed method offers prediction results with sufficient accuracy and shows high computational efficiency.

Structure-type classification and flexibility-based detection of earthquake-induced damage in full-scale RC buildings

Detecting early damage in civil structures is highly desirable. In the area of vibration-based damage detection, modal flexibility (MF)-based methods have proven to be promising tools for promptly identifying changes in the global structural behavior. Many of these methods have been developed for specific types of structures, giving rise to different approaches and damage-sensitive features (DSFs). Although structural type classification is an important part of the damage detection process, this part of the process has received little attention in most literature and often relies on the use of a-priori engineering knowledge. Moreover, in general, experimental validations are only performed on small-scale laboratory structures with controlled artificial damage (e.g., imposed stiffness reductions). This paper proposes data-driven criteria for structure-type classification usable in the framework of MF-based damage identification methods to select the most appropriate algorithms and DSFs for detecting and localizing structural anomalies. This paper also tests the applicability of the proposed classification criteria and the damage identification methods on full-scale reinforced concrete (RC) structures that have experienced earthquake-induced damage. The considered structures are a seven-story RC wall building and a five-story RC frame building, which were both tested on the large-scale University of California, San Diego-Network for Earthquake Engineering Simulation (UCSD-NEES) shaking table.

Modeling of opening for realistic assessment of infilled RC frame buildings

Openings provided to meet functional requirements are often neglected in analytical assessment of Un-Reinforced Masonry (URM) infilled Reinforced Concrete (RC) frame buildings, mostly due to unavailability of simplified comprehensive model to simulate its effect. Ignoring presence of opening in infills results unrealistic assessment of seismic response for these popular building typologies, as opening reduces the strength and stiffness of the composite frame. Several reduction factor models have been developed over the years to account effect of opening in infills. In the present study efficacy of five such models of opening have been investigated which can be used by design practitioners for simulation of opening with sufficient accuracy in predicting the response of composite frame. Extensive analytical study has been conducted on a set of mid-rise and high-rise Indian infilled RC frame buildings considering various realistic combinations of openings by varying size, shape of doors and windows. The study revealed that increasing opening in infills significantly affects the seismic performance, and consequent fragility thereby reduces lateral strength, stiffness, ductility, while increasing fundamental time period, overall deformation capacity and damage probability.

Progressive collapse analysis of RC frame building based on Pseudo-Dynamic (PsD) testing with sub-structuring

Accidental loading coming from either natural or anthropic hazards can have serious consequences on civil engineering structures capacity and can lead to progressive collapse (PC). In the case of frame buildings, PC is a subject of interest to assess the residual risk of exposure to death for people inside. PC analysis on large structures is rather performed from a numerical point of view. Experimental tests are often expensive and complicate to setup (dynamic response, removal of the load-bearing element, size of the experiment, etc.). In this paper, the use of Pseudo-Dynamic (PsD) testing combined with sub-structuring technique is proposed. It allows to account for the dynamic response of the entire structure by only testing (quasi-statically) the critical part of the building. In order to demonstrate the applicability of the method to PC, a classic central column removal scenario is considered and applied on a Reinforced Concrete (RC) structure. The latter is a two-bay and three story frame building. The bending response of the RC beam directly connected to the removed load-bearing member is investigated. Only this part (the RC beam) is experimentally tested while the rest of the structure is simulated by finite element analysis within a dynamic framework. The quasi-static response of the beam is measured and interacts with the integration scheme (α Operator Splitting type) to calculate, inter alias, the inertial forces contributions and the displacement fields within both numerical and experimental domains. To validate the approach, a finite element model based on multifiber beam theory is used. The results comparison underlines a very good agreement between both PsD tests and numerical simulations in all configurations considered, in particular the ability of the PsD approach to account for inertial effects within the structural response. It demonstrates the interest to use such a method within the context of PC analysis. More specifically, the method could prove particularly effective to assess Dynamic Amplification Factors (DAF), used for structural design by accounting for PC potential effect (at least within American guidelines).

Seismic performance of mid-rise reinforced concrete buildings in Izmir Bayrakli after the 2020 Samos earthquake

On October 30th 2020, offshores of Samos Island, Greece was hit by a shallow earthquake of Mw = 6.9 moment magnitude. Located 76 km away from the earthquake’s epicenter, the mid-rise reinforced concrete (RC) building stock of the densely populated Izmir Bayrakli district experienced the most severe structural damage. Although the horizontal peak ground acceleration recorded at the site (PGA = 0.11 g) was well below design values recommended by the past and the present Turkish seismic codes, many buildings suffered heavy damage and 12 buildings collapsed, resulting in a death toll of 117. This paper aims to identify the seismic performance of mid-rise infilled RC frame buildings in Bayrakli by investigating the ground motion recordings, local soil conditions, characteristics of the building stock and the observed damages. The structural performance of 140 RC buildings between 7 and 12 stories that have exhibited poor performance during the earthquake was inspected in detail based on the field surveys conducted right after the earthquake. A database was created documenting the number of stories, major seismic deficiencies, date of construction, geographic coordinates, damage state of structural members and masonry infill walls of the inspected buildings. The localization of structural damage could be partially attributed to the amplified long-distance seismic waves for 0.5–1.5 s periods range due to local soil conditions and basin effects. Seismic vulnerabilities, structural deficiencies and construction quality of the buildings played a significant role in the experienced damage intensity. The influence of infill walls on the seismic performance of RC frame buildings is also clearly observed for code-compliant as well as aseismic buildings.

Fragility curves for different classes of existing RC buildings under ground differential settlements

Existing reinforced concrete (RC) buildings can be affected by different actions that can induce permanent or transient effects on them. While applications concerning the seismic vulnerability of existing RC buildings have been largely proposed in literature, the evaluation of the structural vulnerability because of hazards different from earthquake has been less dealt with. The focus of this work is to estimate the probability that the simulated RC buildings stock could reach a given Limit State for a certain intensity of imposed monotonically increasing ground differential settlements. A set of simulated FEM models, considering the geometrical and mechanical uncertainties in the representation of the existing RC frame buildings designed only for gravitational loads, has been created. The structural frames differ from each other for geometrical features and mechanical materials properties, obtained through a simulation process. The non-linear behavior of columns and beams is considered by applying a modeling approach specifically elaborated for RC members with plain bars. A FEM model for each simulated structural frame has been developed using the Open Application Programming Interface by using the programming and numeric computing platform MATLAB to run the modelling software SAP2000. Time by time, by scaling up the amplitude of the imposed base displacements, a non-linear static incremental procedure has been implemented. At each step of the analysis, a code-based seismic safety assessment has been carried out with reference to a specific ultimate Limit State considered in the Italian and European codes. The goal of the analysis has been to find the values of the significative structural response parameters (identified in this work as the maximum differential settlement and the deflection ratio) at the onset of the selected Limit State by using the critical demand to capacity ratio. Considering that these values are lognormally distributed, the structural fragility is then derived, showing how the vulnerability of the considered RC buildings stock is affected by the impact of the geometrical features and by the application direction of the differential settlements.

In-Plane Seismic Response of Autoclaved Aerated Concrete Block Masonry-Infilled Reinforced Concrete Frame Building

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