Reinforced Concrete Buildings Research Articles

Review Paper on Seismic Analysis of Multi-Storied Reinforced Concrete Building with Fluid Viscous Dampers

Abstract: Frequent earthquakes around the world and the large number of buildings at risk have made it essential to focus on controlling how structures respond to these events. This demand has driven the increased use of structural response control methods globally. This study investigates the seismic performance of multi-storied Reinforced Concrete (RC) Buildings, distinguishing between Regular and Irregular Plan , with a focus on the role of Fluid Viscous Dampers (FVDs). The study aims to quantify the improvements in seismic resilience provided by these damping devices in mitigating the adverse effects of seismic events. Buildings having Regular and Irregular Plans are analyzed, with and without FVD using ETABS2018. The story responses in terms of Pseudo Spectral Accelerations, Maximum Displacement, Story Drift and Story Shear have been compared. The results of the Time History Analysis represent the effectiveness of dampers in improving the structural response and the damping demand on structural systems

Impact of Various High Intensity Earthquake Characteristics on the Inelastic Seismic Response of Irregular Medium-Rise Buildings

In the twenty-first century, the seismic design of buildings seems to have become a fully recognized topic. There are guidelines and standards which should be taken into account by designers in seismic areas. Designers using modern international guidelines have ascertained that the behavior of structures is not as expected. New challenges in the construction industry result in the construction of structures with new, unusual shapes. These are structures that do not meet the assumptions of safe construction in seismic areas. Contemporary buildings are also characterized by their irregular distribution of structural elements. Such solutions are not beneficial from the point of view of seismic engineering and can lead to reduced dynamic resistance and damage in such structures. In this paper, a five-storey, irregular-shaped reinforced concrete (RC) building model was subjected to different earthquakes with varying magnitudes, PGA (peak ground acceleration) and PGV (peak ground velocity) values, and durations of the intense shock phase. Once the model was verified using previous in situ measurements, the building model was subjected to five earthquakes. A numerical nonlinear analysis of the building was performed using a verified FEA (finite element analysis) model in the time domain through non-linear time history analysis with the Broyden–Fletcher–Goldfarb–Shanno (BFGS) method. The building’s dynamic properties were measured using various methods of excitation. The model was influenced, among others, by two far-field representative events caused by the last earthquake in Turkey, which resulted in strong ground motion. The analysis results identified the locations of structural damage and allowed for the assessment of the structure’s dynamic resistance. The results of the calculations prove that the duration of the intensive phase of extortion is one of the reasons for building damage in earthquake-prone areas. Building damage occurs with earthquakes that are characterized by an intensive phase of excitation with a long duration and high values of velocity in the earthquake components. The article highlights the inadequate dynamic resistance of the building, leading to excessive displacements and unfavorable structural solutions. Damage to buildings at this earthquake intensity caused damage to the load-bearing structure, which was not designed for such intensities. This paper is a research report with a specific case study of medium-rise irregular RC buildings.

Seismic Response of Open Ground Story Reinforced Concrete Buildings, Considering with Soil-Structure Interaction

This study investigates the seismic behavior of open-ground story (OGS) reinforced concrete buildings with soil-structure interaction (SSI) using SAP2000. The study mainly focused on mid-rise (8-storey) and low-rise (4-storey) OGS buildings, incorporating different masonry infill materials such as brick, concrete blocks, and autoclaved aerated concrete (AAC) blocks. Selected ground motions from the Bhuj, El Centro, and Chi-Chi earthquakes were utilized to simulate varying seismic intensities and frequency content. Critical parameters such as top-story displacement and inter-story drift are analyzed to assess the structural safety and serviceability of RC buildings. The results demonstrate that both OGS coupled with SSI and masonry infill type significantly affect the displacement and drift, with mid-rise buildings showing more pronounced impacts. Furthermore, ground motion characteristics are critical in producing different response patterns. The study highlights the importance of considering SSI, infill materials, and ground motion characteristics in the design of OGS buildings to enhance earthquake resilience and reduce seismic damage.

Experimental Evaluation of an Innovative Connection for the Reinforcement of Existing Infilled RC Buildings

The retrofitting of existing reinforced concrete (RC) buildings with cross-laminated timber (CLT) panels presents a promising approach for enhancing seismic performance and overall structural resilience. However, effective integration of CLT with existing RC structures poses significant challenges, particularly concerning the design of connections between CLT panels and the RC structure. This paper introduces a novel connection that addresses these challenges by focusing on both structural and architectural considerations. Structurally, the connection is engineered to provide optimal stiffness, strength, and deformation capacity, ensuring robust performance under seismic and dynamic loads. Architecturally, the design incorporates a predefined weak component that facilitates easy access and rapid replacement of damaged parts, thereby reducing downtime and maintenance efforts. The proposed connection was evaluated through a series of monotonic and cyclic loading tests, demonstrating its structural efficiency and reliability. The results indicate that the new connection system not only meets the necessary structural requirements but also offers practical benefits for maintenance and repair, contributing to the overall sustainability and resilience of retrofitted RC buildings. This innovative approach represents a significant advancement in the field of structural retrofitting, providing a viable solution for integrating CLT panels into existing RC frameworks.

AI Analysis of the Thermal Effects on Reinforced Concrete Buildings with Floating Columns

AI Analysis of the Thermal Effects on Reinforced Concrete Buildings with Floating Columns

Local and global integrative retrofitting of reinforced concrete frames using in‐plane buckling steel braces

AbstractTwo large‐scale, single‐storey, single‐bay reinforced concrete (RC) moment frames, designed as per an outdated seismic code to represent a typical framing detail of a four‐storey building, have been tested under displacement‐controlled quasi‐static loading protocol as per ACI 374.1‐05. The RC frames include a plinth beam with brick infill underneath, a slab monolithically cast with the top beam and provision for applying axial load to the column to simulate real construction scenario. One of the frames has been tested as a bare frame, and the second one has been retrofitted with conventional steel braces designed to undergo in‐plane buckling. The size of the brace has been selected based on the result of a nonlinear time history analysis of representative low‐ to mid‐rise open‐ground storey RC buildings. Post‐installed chemical anchors have been utilized to connect the steel braces to the narrow RC frame members following the outcomes of an experimental investigation by the same authors. Local‐level retrofitting by steel jacketing using adhesives has been designed and utilized on columns and beams to achieve the desired seismic response. The seismic performance of the retrofitted frame has been compared with the bare frame in terms of strength, stiffness, ductility, energy dissipation and hysteretic damping. The tests provide insight into the role of the plinth beam, effect of RC slab on the strong‐column weak‐beam aspect and the achievement of the desirable hinge mechanism through a precise design and detailing of global and local level retrofitting technique.

Seismic capacity evaluation of a reinforced concrete frame infilled with precast modular block wall for enhancing the horizontal load

In this study, we propose a new concept for seismic retrofitting using precast modular block walls (PMBWs) to improve and complement the shortcomings of conventional retrofitting methods for reinforced concrete (RC) frames infilled with shear walls, masonry walls, and precast panels. The PMBW retrofitting method maximizes the advantages of factory-produced modular blocks, innovatively enhancing the constructability and integrity of connections between the existing frame and the infilled PMBW. Additionally, the PMBW reinforcement method improves seismic resistance without significantly increasing structural weight, and the required amount of reinforcement can easily be calculated because the strengthening technique involves typical frame infilling. For RC buildings with non-seismic details dominated by shear failure, the application of this seismic reinforcement method readily ensures sufficient strength. A pseudo-dynamic test was conducted on a full-scale two-story frame, based on an existing RC building with non-seismic details, to evaluate the restoring force characteristics, strength enhancement effects, reinforcement strain, and seismic response control capabilities of the PMBW reinforcement system. Based on the pseudo-dynamic test results, the restoring force characteristics for nonlinear dynamic analysis of the PMBW-reinforced specimen were identified. Finally, nonlinear dynamic analysis was conducted using the proposed restoring force characteristics, and the results were compared with the pseudo-dynamic test results. The unreinforced RC frame experienced shear failure at a design basis earthquake magnitude of 200 cm/s2. However, the frame reinforced with the PMBW sustained only minor damage. Even at higher magnitudes under maximum considered earthquake conditions of 300 cm/s2 and large-scale earthquake conditions of 400 cm/s2, only a slight amount of damage was projected from the analysis. Thus, the newly developed PMBW frame infilling system shows great promise for seismic reinforcement.

Realistic modelling of contributions by floor slabs in the earthquake safety assessment of buildings

ABSTRACT The conventional structural design of buildings often neglects the significant contributions of the coupling action of the floor slabs, potentially leading to unsafe designs against seismic actions. The interaction between reinforced concrete (RC) frames and shear walls, especially through slabs, plays a crucial role in the structure’s behaviour under seismic loading. In Australian construction, where wall-type systems are prevalent, it is essential to understand the complex interactions between coupled walls and columns facilitated by slabs. This study addresses this issue by proposing an innovative strain-based model, validated through finite element analysis. The proposed model, when compared with existing simplified models, demonstrates superior accuracy and effectiveness. This innovative approach not only enhances our understanding of seismic behaviour but also offers a straightforward solution that can be easily implemented in practice. Key findings reveal that slab interaction increases material strain and inelastic force capacity while reducing displacement capacity, particularly affecting smaller elements like gravity load-carrying columns. This improved understanding can lead to more effective strategies for enhancing the seismic resilience of RC buildings.

Waste Paint as Admixture for Glass Fiber–Reinforced Concrete Building Façades

Waste Paint as Admixture for Glass Fiber–Reinforced Concrete Building Façades

Seismic Risk Evaluation of Existing Reinforced Concrete Buildings: A Case Study for Çanakkale-Türkiye

Türkiye is in an important earthquake zone, and most of the population is under seismic hazard. The high loss of lives in the past earthquakes indicates that our existing building stock is vulnerable. In this study, a field survey was carried out to determine the existing earthquake risks of reinforced concrete buildings in İsmetpaşa, Barbaros, Cevatpaşa, Kemalpaşa, Namıkkemal, Esenler, and Fevzipaşa Neighborhoods of Çanakkale city center. This study was conducted to specify the regional distribution of risky buildings to be examined by the street survey method called "Simplified methods that can be used to determine the regional risk distribution of buildings" in the implementation regulation of Law No. 6306. For this purpose, 585 reinforced concrete buildings were examined with this method, and the earthquake performance scores of these buildings were determined. The performance scores calculated as a result of reflecting the number of stories, earthquake hazard zone, type of structural system, and structural irregularities of the buildings were evaluated based on different parameters. It was seen that soft stories with values ranging from 50% to 100% and heavy overhangs with values ranging from 37% to 63% were the most common irregularities in existing buildings in Çanakkale.

Effect of prevalent irregular configuration of infills on the seismic collapse of Indian RC buildings

Rapid urbanization and land scarcity obligated the urban population for multi-use of Reinforced Concrete (RC) buildings to meet both residential and commercial purposes together. Un-Reinforced Masonry (URM) infills are often placed irregularly in plan and or elevation of the buildings in some floor(s), particularly in the ground floor to suit the need of occupational requirements accompanied by the inherent irregularities due to openings for doors and windows to meet functional requirements for residence. Seismic performance of infilled frame highly depends upon degree of infill-frame interaction, and it is of utmost importance to classify infilled frame buildings in various Model Building Types (MBTs) based on the type of irregular placement of infills in addition to the parameters affecting seismic performance. Based on field pilot surveys carried out in Indian cities, URM infilled buildings have been classified into 14 different MBTs. Seismic performance of the prevalent categories of MBTs have been evaluated through Incremental Dynamic Analysis (IDA). It has been observed that irregular placement of infills increases the seismic collapse risk significantly, and reduces collapse capacity to approximately 50% as compared to ideal uniformly infilled building. Global collapse occurred due to failure of structural members in the vicinity of irregularity created due to infills.

Machine learning-based approach for assessing the seismic vulnerability of reinforced concrete frame buildings

Recent artificial intelligence (AI) advancements have significantly impacted the field of structural engineering by offering new solutions to enhance safety, efficiency, and cost-effectiveness in the design, construction, and maintenance of infrastructure and urban areas. This study has investigated a machine learning-based approach to estimate the seismic vulnerability of reinforced concrete (RC) building frames. The study utilized a probabilistic technique to assess the simulation of a 4-story RC building frame in the face of epistemic uncertainty. Data was collected using the Monte-Carlo approach, which created a machine learning (ML) model for predicting structural damage. The problem was formulated as both a regression-based and a classification-based model. An artificial neural network (ANN) feed-forward network architecture model was used to solve the classification problems. The optimal number of neurons in the hidden layer was determined to produce the best estimation model. Three different models were combined for the regression model, including LASSO regression, random forest, and gradient boosting, by implementing the stacking generalization. The investigation results indicate that the stacked predicted model exhibits less variance than other ML models. The classification and regression-based algorithms can forecast damage states with a high degree of accuracy, ranging from 87 to 95 percent. In conclusion, the study has demonstrated the effectiveness of machine learning techniques for predicting the seismic vulnerability of RC building frames. With the continued advancement of AI and big data, these methods will likely play a crucial role in the structural engineering field.

Predicting Main Characteristics of Reinforced Concrete Buildings Using Machine Learning

This paper presents a comprehensive study of five machine learning (ML) algorithms for predicting key characteristics of Reinforced Concrete (RC) structural systems. A novel dataset, ModRes, consisting of 9723 examples derived from modal and response spectrum analyses on masonry-infilled three-dimensional RC buildings, was created for ML applications. The primary objective is to develop an ML model using five distinct algorithms from the literature, capable of concurrently predicting torsional irregularity, modal participating mass ratio (MPMR), and the fundamental period in a 3D environment, while accounting for the influence of infill walls. Additionally, the study aims to determine the applicability of pushover analysis (POA) without the need for extensive numerical modeling and analysis. This approach optimizes the preliminary design process with minimal computational effort, providing valuable insights into dynamic and torsional responses during seismic events. The Categorical Boosting algorithm demonstrated outstanding performance, achieving R2 values of 0.977 for torsional irregularity, 0.997 for the fundamental period, and 0.923 for MPMR on the test dataset. It also successfully predicted POA applicability with an error rate of only 1.36%. This study highlights the practical application of ML algorithms, underscoring their effectiveness in structural engineering.

Failure Probability-Based Optimal Seismic Design of Reinforced Concrete Structures Using Genetic Algorithms

Artificial intelligence (AI) has enabled several optimization techniques for structural design, including machine learning, evolutionary algorithms, as in the case of genetic algorithms, reinforced learning, deep learning, etc. Although the use of AI for weight optimization in steel and concrete buildings has been extensively studied in recent decades, multi-objective optimization for reinforced concrete (RC) and steel buildings remains challenging due to the difficulty in establishing independent objective functions and obtaining Pareto fronts. The well-known Non-Dominated Sorting Genetic Algorithm II (NSGA-II) is an efficient genetic algorithm approach for multi-objective optimization. In this work, the NSGA-II approach is considered for the multi-objective structural optimization of three-dimensional RC buildings subjected to earthquakes. For the objective of this study, two function objectives are considered: minimizing total cost and the probability of structural failure, which are obtained via several nonlinear seismic analyses of the RC buildings. Beams and columns’ cross-sectional dimensions are selected as design variables, and the Mexican Building Code (MBC) specifications are imposed as design constraints. Pareto fronts are obtained for two RC-framed buildings located in Mexico City (soft soil sites), which demonstrate the efficiency and accuracy of NSGA-II for structural optimization.

Code-based brittle capacity models for seismic assessment of pre-code RC buildings: comparison and consequences on retrofit

The existing Reinforced Concrete (RC) buildings stock is often characterized by a significant seismic vulnerability, due to the absence of capacity design principles, even in regions with high seismic hazard, such as Italy. Approximately 67% of existing RC buildings in Italy have been designed without considering seismic actions (GLD), resulting in very low transverse reinforcement amount in beams and, particularly, in columns. Additionally, beam-column joints typically totally lack stirrups. Consequently, shear failures under seismic actions are very likely for this pre-code building typology, often limiting their seismic capacity. However, the assessment of shear failures in beams/columns or joints varies significantly from code to code worldwide. The main goal of this work is to quantify the impact of different code-based brittle capacity models on the seismic capacity assessment and retrofit, focusing on GLD Italian pre-1970 RC buildings. This comparative analysis is carried out by first considering three current codes, emphasizing their, even significant, differences: European (EN 1998-3-1. 2005), Italian (D.M. 2018), and American (ASCE SEI/41 2017) standards. Then, shear capacity models prescribed by the current drafts of the next generation of Eurocodes are implemented and compared to the current models. The assessment includes: (i) a parametric comparison among models; (ii) the evaluation of case-study buildings capacity in their as-built condition and after shear strengthening interventions. The latter is performed on 3D “bare” models, due to the lack of practical guidance in most codes on modelling masonry infills.

Evaluation of Earthquake Performance of Reinforced Concrete Buildings with Fuzzy Logic Method

Reinforced concrete building is a type of building whose structural system consists of reinforced concrete columns, beams, wall wall, slabs and foundations. Due to the strong earthquakes in our country, it has been observed that reinforced concrete buildings have been severely damaged or collapsed from past to present. The evaluation of buildings after earthquakes and their performances are quite important for the safety of life and property. In the literature, different methods have been developed for post-earthquake evaluation of buildings, either low-cost and fast or slow and high-cost and tool-demanding. In this study, in order to overcome the gap in the literature, the evaluation of earthquake performance of buildings with fuzzy logic method is discussed. In this context, the performance of the building was evaluated by taking into account the concrete compressive strength, number of floors, ground floor area, area of column and shear walls, ground floor area and architectural parameters. The data of 18, 28 and 146 buildings affected by the earthquakes in Afyon, Bingöl and Van provinces in 2002, 2003 and 2011, respectively, were used in the study. Out of the total 192 building data, 94 buildings were processed as data and fuzzy logic rules were applied. The remaining 98 buildings were tested with this method. The buildings considered are light, moderate and severely damaged or collapsed. Matlab program was used in the study. The method and result used in the study are in the class of fast and second stage methods in the literature, which are reliable but do not reflect the final result. With the method revealed in the study, the damage status of reinforced concrete buildings can be determined quickly and reliably. In this context, the buildings were evaluated as no damage/slight, moderate and severely damaged or collapsed. According to the results, the correct estimation rate of the damage status of 98 buildings was found to be 88%. It is seen that the fuzzy logic method can predict building performances at a quite high rate. Compared to the existing second stage assessment methods in the literature, this result is more conservative.

Earthquake Functional Recovery in Modern Reinforced Concrete Buildings

Earthquake Functional Recovery in Modern Reinforced Concrete Buildings

Seismic Performance of Multistory Reinforced Concrete Buildings by Pushover Analysis

Abstract: In this investigation the analysis of G+4, G+11 and G+21 building is situated in New Delhi (Zone IV. The seismic analysis of of G+4, G+11 and G+21 building as per IS 1893-2002. In this research pushover analysis was performed in SAP 2000 and after that is designed as per IS 456-2000 for different loads. This analysis gives better understanding seismic performance of building & also shows damage or failure of buildings. The building performance level is determined by pushover curve & demand curve. The result shows that the failure is noticed in the column of ground storey of the building. After that enlarged amount of reinforcement in the ground story the buildings have reached life safety performance level.

Cross‐laminated timber for seismic retrofitting of RC buildings: Substructured pseudodynamic tests on a full‐scale prototype

AbstractThis paper presents an experimental study on an innovative timber‐based retrofit solution for reinforced concrete (RC) framed buildings, with or without masonry infills. The intervention aims to enhance seismic resistance through a light, cost‐effective, sustainable, and reversible approach integrating energy efficiency upgrades. The method employs cross‐laminated timber (CLT) panels as infills or external retrofitting elements, mechanically connected to the RC frame through steel fasteners. The system is combined with thermal insulation for improved energy efficiency. The seismic performance of the proposed retrofit technique was assessed experimentally on a full‐scale building model at the European Laboratory for Structural Assessment (ELSA). The experiments included tests on two five‐story building configurations: a masonry‐infilled RC building as a reference and the same structure strengthened with CLT panels. Each building was subjected to unidirectional earthquake simulations of increasing intensity using the pseudodynamic (PsD) testing method with substructuring. The physical substructure of the hybrid model consisted of the first story of a two‐story mockup built and retrofitted in the laboratory, while stories two to five were simulated numerically. The paper discusses major observations from the tests, comparing the damage evolution and hysteretic responses of the two configurations. The experiments yielded promising results, showing that the suggested retrofit solution significantly increased displacement and energy dissipation capacity. The retrofitted building survived earthquake intensities up to 50% higher than the non‐retrofitted counterpart, exhibiting only slight structural damage. These pioneering experiments provide compelling data on the high effectiveness of the proposed CLT‐based retrofit system in enhancing the seismic performance of full‐scale RC buildings.

The Influence of Open-Ground Floors on the Impact of RC Columns Due to Seismic Pounding from Adjacent Lower-Height Structures

The substantial influences of masonry infills used as partition walls on the seismic behavior of multistory reinforced concrete (RC) structures have long been recognized. Thereupon, in this study, considering open-ground floors due to a lack of infills (pilotis configuration), the structural pounding phenomenon between adjoining RC buildings with unequal story levels and unequal total heights is investigated. Emphasis is placed on the impact of the external columns of the higher structure, which suffer from the slabs of adjoining shorter buildings. The developing maximum shear forces of the columns due to the impact are discussed and compared with the available shear strength. Furthermore, it is stressed that the structures are partially in contact, as is the case in most real adjacent structures; therefore, the torsional vibrations brought about due to the pounding phenomenon are examined by performing 3D nonlinear dynamic analyses (asymmetric pounding). In this study, an eight-story RC frame structure that is considered to be fully infilled or has an open-ground floor interacts with shorter buildings with ns stories, where ns = 6, 3, and 1. Two natural seismic excitations are used, with each one applied twice—once in the positive direction and once in the negative direction—to investigate the influence of seismic directionality on the asymmetric pounding effect. Finally, from the results of this study, it is concluded that the open-ground story significantly increases the shear capacity demands of the columns that suffer the impact and the inelastic rotation demands of the structure, whereas these demands further increase as the stories of the adjoining shorter building increase.