Seismic Behavior Of Buildings Research Articles

The Seismic Behavior of Buildings with Flat Slab Systems under Near-Fault Ground Motions

It is well known that structural displacement or ductility demands of structures subjected to near-fault ground motions are generally greater than ordinary ground motions. Therefore, the effect of earthquake records in the near region on the seismic behavior of structures has been widely studied in the last decades. Peak ground acceleration (PGA) is an important key parameter, which determines structural behavior. However, structural behavior depends on the distance of the structure to the fault zone, the ratio of peak ground velocity (PGV) to peak ground acceleration, the velocity pulse duration of ground motion, and the natural period of the structure. In this study, the seismic behavior of buildings with flat slab systems was investigated under near-fault ground motions. Linear time history analysis was performed for a 30-storey building designed according to TBEC-2018 using SAP 2000 finite element analysis software. Results were compared with the behavior of the building with a solid slab system. It is concluded that the ratio of PGV/PGA is very effective on the flat slab systems.

Seismic behaviour of reinforced-masonry aggregate under different types of interaction between adjacent dwellings

Assessing the seismic vulnerability of existing buildings is an essential task for the management of earthquake disasters. For this purpose, the seismic behaviour of buildings is usually determined under the assumption of isolated conditions, although aggregate structures are one of the most common typologies found in urban centres. This study aims to investigate the nonlinear static behaviour of aggregate dwellings consisting of grouted reinforced concrete block configurations commonly observed in San José, Costa Rica. This research investigates the use of several strategies to model connections between adjacent buildings which are typically found in modern building practises in this country. The methodology used here to analyse the seismic behaviour of isolated and row-aggregated dwellings reveals significant differences in their response under seismic loads, especially when acting perpendicular to the aggregate. The study reveals that the type of interaction considered between adjacent buildings has a very important impact on the seismic capacity and failure mechanisms of the aggregated structures. This procedure can also be applied to the vulnerability assessment and retrofit of existing aggregates.

Optimal Bracing Type of Reinforced Concrete Buildings with Soil-Structure Interaction Taken into Consideration

This study aims to investigate the impact of soil-structure interaction (SSI) on the seismic behavior of reinforced concrete buildings. An advanced numerical model for SSI was developed and verified using ABAQUS software. The seismic response of a 12-story building on four types of soil (rock, dense soil, stiff soil, and soft soil) was examined using a Normalized Response Spectra based on the Moroccan paraseismic regulation RPS 2011. The global lateral displacement, inter-story drift, and period were compared for two types of bracing (column and shear wall). The results show that SSI has a significant impact on the seismic behavior of buildings, and the seismic responses of soil-structure systems with column and shear wall bracing are quite different. The research contributions of this paper include developing an advanced numerical model for SSI, examining the impact of SSI on the choice of bracing for reinforced concrete buildings, and providing guidance on the most reliable bracing method for structures of various heights and soil types. The study's findings have important implications for seismic design and can help improve the safety and reliability of buildings in earthquake-prone regions. The study also highlights the importance of considering SSI in seismic design and the need for guidelines that describe the bracing systems to be used based on the structure's height and type of soil. Doi: 10.28991/CEJ-2023-09-06-06 Full Text: PDF

Seismic Behaviour of Building with Soft Storey: Review

Abstract: The high-rise building in which ground storey consists of open space is known as building with soft floor. Such floor plays an important role in seismic performance of the building. This is due to the abrupt changes in lateral stiffness and strength caused by such storey. In the present era there is increase in population, finding parking for flats in congested areas has become a significant issue. As a result, erecting multistory structures with an open first floor is now a widespread practice. These Buildings that have all upper storeys enclosed by masonry walls but no infill masonry walls in the ground story are referred to as "Soft Storey" or "Open Ground Storey Buildings." Compared to regular buildings, irregular structures the drift is observed to be effectively reduced by larger columns, while the shear force and bending moment on the first floor are increased. During a violent earthquake, the Soft Storey buildings function poorly. Understanding the behavior of is this study's primary goal to the building in a seismically active area and to assess the effects of Storey overturning moments, Storey drift, displacement, and design Base shear. For comparison, G-15 story building with five completely distinct shapes a square, an L-shaped building, a Tshaped building, a plus shape building and a C-shaped building is used. ETABS 2018 version is used to analyze the entire set of models. Dynamic Analysis has been examined in the current work to assess the deformation of all five-shape building with and without soft storey considering at different level. When the soft story is offered at a higher level, displacement is reduced. Several studies on this subject that have been done in the past are reviewed in this paper. Reviewing research papers let us know about the conclusive results, which served as the basis for the objective of our future study.

Fragility Functions for Reinforced Concrete Structures Based on Multiscale Approach for Earthquake Damage Criteria

For seismic risk analysis, reliable predictions and estimations of earthquake damage and seismic behaviour of buildings are essential. A common method is the use of fragility curves. In this paper, fragility functions are developed based on various numerical damage criteria for five defined damage grades, from slight to destruction. The proposed new multiscale approach establishes a correlation between observed damage patterns due to foreign earthquakes and the seismic response of the building using thresholds for material-specific and global characteristics. This approach takes into account various possible damage patterns on different scales more comprehensively than the well-known approach of displacement criteria. Moreover, the approach is universal and adaptable for building classes as well as region-specific material and system characteristics. Several damage criteria with their defined limit values are assigned to the five proposed damage grades, whereby quantity and distribution of the exceeded criteria are relevant, since the first occurrence does not always lead to damage. With the new approach, damages that are not evident in the pushover curve in terms of strength degradation can be detected and taken into account for the damage thresholds. The derived displacement values associated with the damage levels are the basis for developing fragility functions. The results—damage criteria, pushover curves with damage grades, capacity curves as well as fragility functions and parameters—are presented for a four-storey reinforced concrete frame building. These results are discussed and validated with data from the literature. Comparisons to existing fragility functions in the literature show that our developed fragility functions are mostly located in the middle range, graphically as well as for the curve parameters. This specific example was chosen to present our multiscale approach, but for general building classes, numerous simulations with varying characteristics are essential and result in a higher standard deviation of the final fragility curves.

A model for determining the arrangement and geometric specifications of infill walls in the architectural design to improve the seismic behavior of buildings

ABSTRACT Experiences of past earthquakes show that the infill wall is one of the non-structural elements which has the highest collapse potential of the structure. Although architects are responsible for designing the form and arrangement of walls, little research has been done in this regard with the aim of architectural design. In this research, a method was developed to control the infill walls in the basic architectural design. In this method, architectural design features are preserved, and only by applying minor modifications to the specifications of walls, undesirable effects such as short column, soft story, and torsion are prevented and without using more materials, additional potential for seismic resistance of the building is provided. For this method, two accurate and approximate models were developed. In the accurate model which includes five algorithms, a structural model is required, so close collaboration between architect and structural engineer is necessary. In the approximate method which includes four algorithms, only geometric specifications of architectural design are required and architects can control the effects of infill walls on the structure. The results of the practical test of the approximate model indicated that this model can be used by various groups of architects. This model will not prevent the creativity of architects and the designer has a great degree of freedom in applying solutions.

Seismic Behavior of Micropiles and Micropiled Structures Used for Increasing Resilience: A Literature Review

The aim of this paper is to present the relevant information and development available in the scientific literature regarding the seismic behavior of micropiles (MPs) and micropiled structures (MPed). The seismic behavior of MPs is not very well studied, but MPs are used in retrofitting of old buildings and for new resilient buildings, and in terms of seismic behavior they have a high potential. Additionally, their association with seismic dampers for improving the seismic behavior of buildings is not yet fully studied and it represents a major topic of interest for both new structures and historical monuments. After the introductory part, the paper describes all relevant information regarding MPs, as types and technology, seismic behavior, applications for increasing seismic resilience, and experimental and numerical modeling.

Seismic Vulnerability Assessment and Strengthening of Heritage Timber Buildings: A Review

Recent studies highlight the potential impact of earthquakes on cultural heritage sites and monuments, which in turn yield significant adverse impacts on economies, politics, and societies. Several aspects such as building materials, structural responses, and restoration strategies must be considered in the conservation of heritage structures. Timber is an old organic construction material. Most of the historic timber structures were not designed to withstand seismic forces; therefore, the seismic vulnerability assessment of heritage timber structures in areas with high seismic hazard is essential for their conservation. For this purpose, different strategies for the numerical modeling of heritage timber buildings have been developed and validated against tests results. After performing seismic analysis using detailed analytical methods and predicting the susceptible structural components, strengthening techniques should be utilized to mitigate the risk level. To this aim, various methods using wooden components, composite material, steel components, SMA etc., have been utilized and tested and are reviewed in this study. There are still some gaps, such as full-scale numerical modeling of strengthened buildings and investigating the soil–structure interaction effects on the seismic behavior of buildings that should be investigated.

Seismological Aspects and Seismic Behavior of Buildings During the M 7.3 Western Iran Earthquake in Sarpol-e-zahab Region

Seismological Aspects and Seismic Behavior of Buildings During the M 7.3 Western Iran Earthquake in Sarpol-e-zahab Region

Assessment of seismic performance of RC frame structure with masonry infill panels partially uncoupled from the surrounding frame members

The present study numerically analyses the influence of physical and mechanical properties of the materials used for masonry infill panels upon the seismic response of low rise reinforced concrete frame structure. A four-storey residential building (benchmark), located in Timisoara, a moderate seismic area, has been designed according to the current Romanian design codes. Then, infill panels considered uncoupled from the frame members along their lateral and upper edges, have been added to the structure. Infill panels have been investigated in four variants, by using 2 types of masonry units (hollowed ceramic blocks and AAC), alternatively built with mortars specific for regular bed joints (G) and thin bed joints (T), for which a comparative modal response spectrum analysis has been carried out. The seismic behaviour of buildings in all these cases has been analysed in terms of peak inter-storey drifts under two limit states and of the out-of-plane strength of infill panels. The results show that the peak inter-storey drifts reductions compared to the benchmark structure are up to 59% at SLS, and 61% at ULS. Regarding the out-of-plane behaviour of the infill panels it was noted that safety verification is fulfilled only for one of the abovementioned cases. As a final remark, the results obtained in this study highlight the importance of physical and mechanical properties of the masonry infill panels in the assessments of seismic response of frame structure buildings.

Effects of Architectural Irregularities on the Seismic Behavior of Buildings

Cooperation between the architect and the civil engineer has nowadays become essential in any project for the client’s requests’ sake. This study was made to show this idea’s importance and beneficial consequences. For this purpose, a 40-story dual-system high-rise building has been designed to resist moderate seismic and high wind loads. Three main models were formed: Starting with the net model, which is the regular model, followed by the mass irregularity models that were generated for the luxury floor desires (this irregularity was placed in two different locations, namely at the top and middle position), ending with the soft story irregularity models that were cited in the building’s middle and bottom for the gym floor’s need. The positions for each irregularity were tested and compared to those of the regular model under the effect of seismic load on one hand and under the influence of three different wind loads on the other. The required wind loads studied in this article were assigned from the wind speeds of 80, 100 and 120 mph. For these models’ analysis, RSA using finite element method on ETABS was used.The results exhibited that the peak wind speed this building held was 110 mph for both irregularities. Furthermore, the seismically-designed high-rise buildings might not be safe enough to resist a wind load speed of 120 mph. In addition, the middle location is the most preferable locus for these irregularities to occur regarding wind and seismic loads because of its minor displacement, drift and base shear. Besides, it ensured the economic cost of the mass irregularity ($1,706,380), which is in turn less than that of the top position ($1,790,187). The same applies for the stiffness irregularity cost, requiring a budget of $1,632,310 in the middle position but an expense of $1,676,368 for the bottom locus. Although the irregularity’s perfect location seemed unfamiliar, it pursues the sake of the client, the architect and the civil engineer alike.

Seismic behavior of buildings in Mexico City during the 2017 Puebla–Morelos earthquake

Seismic behavior of buildings in Mexico City during the 2017 Puebla–Morelos earthquake

Experimental study of the effects of slab openings on seismic behaviour of buildings

Experimentation by producing three-dimensional samples for understanding the seismic behaviour of a structure takes a significant amount of time and these experiments may be highly complicated. Based on literature, the seismic behaviour of structures with slab openings usually was represented by analytical assessments instead of three-dimensional experimental studies. Moreover, the limiting values of slab openings vary greatly between earthquake regulations. This variability has made it important for experimental studies. For this purpose, a total of 5 reinforced concrete carrier system models, with different slab opening ratios, were produced at 1/2 scale. As a result of the study, it was observed that in cases where there were 25% or more openings in the slab, rigid diaphragm behaviour decreased in the structure. It was recommended that for analyses of these types of building systems that the finite element method, based on the assumption of an elastic diaphragm rather than the assumption of a rigid diaphragm, be used.

Assessing the soil-structure interaction effects by direct method on the out-of-plane behavior of masonry structures (case study: Arge-Tabriz)

Soil-Structure Interaction (SSI) is an outstanding factor that influences the linear and nonlinear performance of any structure, and it can be taken into account as one of the most important and effective considerations on the seismic behavior of buildings. On the other hand, historic masonry buildings are specific and important structures, which are significantly affected by SSI. Preservation of these buildings is one of the main demands of every culture and every society; and evaluating the behavior of these buildings under natural events such as earthquake, considering aforementioned SSI phenomenon, is an essential step, in this regard. In this paper, the impact of SSI on the out-of-plane behavior of an ancient building in Iran, named Arge-Tabriz, has been investigated utilizing Finite Element Method (FEM). Modal and nonlinear Time-History (TH) analyses results revealed that SSI has a significant decreasing effect on the acceleration response due to removing the effective mode vectors from the resonance area of the acceleration response spectra. On the contrary, SSI has a remarkable increasing impact on the displacement response of Arg’s walls according to the displacement response spectra.

Seismic Behaviour of RC Building with Raft Foundation in the Ganges Basin, India

Many highly populated and important cities of India are situated in the Ganges basin. Deep alluvium deposit of this basin enhances the earthquake vulnerability of these cities due to amplification of seismic energies in the case of an earthquake. Raft foundations are generally provided for critical facility buildings due to their perceived effectiveness against differential settlement during earthquakes. However, the literature available on seismic behaviour of buildings with raft foundation considering soil deformability is relatively limited. In this context, a full three-dimensional finite element model of a four-storeyed building with raft foundation considering the typical layered soil profile of the Ganges basin has been developed in this study. The effects of different seismic parameters on the structural responses and moments induced in the raft have been studied with ground motions from 10 different earthquakes. Since the alluvium deposit of the Ganges basin is prone to get liquefied, effects of liquefaction of soil on the building with raft foundation have been considered simplistically. The results show that the raft foundation reduces the lateral displacement of the structure considerably. However, an increase in the vertical settlement of the raft in case of liquefiable soil is a matter of concern.

The Effects of Temporary Tower Cranes on the Construction Process and Seismic Behavior of Reinforced Concrete Buildings

When space is limited on project site to install a tower crane for the construction of high and mid-rise buildings, project managers have to deal with the challenge of assembling such crane somewhere in the middle of the building, leaving an opening in the floor slabs. Nevertheless, there is limited evidence about the effects of this type of temporary structure on the seismic behavior of buildings. The study analyzes the effect of having temporary openings in slabs of reinforced concrete buildings, when tower cranes need to be mounted inside a building. A structural intervention on the buildings' slabs was simulated to resemble the temporary openings required to install a tower crane. Results indicated that seismic deformations were almost the same with and without the slab opening, which enables the installation of tower cranes through the slabs of reinforced concrete buildings, without affecting serviceability levels and seismic behavior of buildings.

A transferable remote sensing approach to classify building structural types for seismic risk analyses: the case of Val d'Agri area (Italy)

This study proposes a methodology based on machine learning (ML) algorithms for rapid and robust classification of building structural types (STs) in multispectral remote sensing imagery aiming to assess buildings’ seismic vulnerability. The seismic behavior of buildings is strongly affected by the ST, including material, age, height, and other main structural features. Previous works deployed in situ data integrated with remote sensing information to statistically infer STs through supervised ML methods. We propose a transferable methodology with specific focus on situations with imbalanced in situ data (i.e., the number of available labeled samples for model learning differs largely between different STs). We learn a transferable model by selecting features from an exhaustive set. The transferability relies on deploying geometric features characterizing individual buildings; thus, the model is less sensitive to domain adaption problems frequently induced by e.g., changes in acquisition parameters of remotely sensed imagery. Thereby, we show that few geometry features enable generalization capabilities similar to models learned with a large number of features describing spectral, geometrical or contextual building properties. We rely on an extensive geodatabase containing almost 18,000 building footprints. We follow a Random Forest (RF)-based feature selection strategy to objectively identify most valuable features for prediction. Furthermore, the problem of unbalanced classes is addressed by adopting two approaches: downsampling the majority class and modifying the classifier internally (weighted RF). The implemented model is transferred on the challenging urban morphology of the Val d’Agri area (Italy). Results confirm the statistical robustness of the model and the importance of the geometry features, allowing for reliable identification of STs.

Analysis of One Bay Residential Building with Combined RCC Frame and Load Bearing Wall Structures

The major purpose of this study is to justify construction method of a hybrid structure in core area with construction complexity due unsafe excavation conditions and tries to define its rigidity and strength. Both RCC and Frame structure transfer same load to ground through foundation but the transfer mechanism varies. In some practical condition, building construction should be carried out in compact areas with unsafe adjoining building where adequate excavation for foundation cannot be carried out. In such cases, one bay hybrid structure is proposed for construction with combined RCC frame structure and load bearing walls. In these combined cases, both structures works as same unit to transfer building load but the transfer pattern varies. The variable load transfer pattern is due to discontinuity in structural system which also effect on seismic response of the building. The placement of a masonry load bearing structure in RCC frame structure varies design of all structural components of the building. To study actual behavior of hybrid structure in various load condition and introducing cost minimization techniques of buildings structural analysis was carried using ETABS 2016 with composite structural arrangement and with induction of load bearing wall as structural component. By which seismic behavior of building in both cases was obtained as well as reduction in rebar percentage and dimensional reduction of structural components can be achieved.Journal of the Institute of Engineering, 2017, 13(1): 117-124

Seismic Behavior of Domestic Piloti-type Buildings Damaged by 2017 Pohang Earthquake

Pohang earthquake occurred on November 15, 2017, with a magnitude of 5.4. The damage of the structure caused by the Pohang earthquake was the most significant in 4-story piloti-type buildings, where the damage patterns were different according to the location of columns and walls at the first story. One building with a staircase at a corner shows shear failure at columns, and Another building with a staircase in the middle shows no failure or shear failure at staircase walls. Therefore, two different piloti-type buildings were selected; one has a staircase at a corner and another has in the middle, and the seismic behavior of the buildings were examined by nonlinear dynamic analysis applying a ground motion measured at Pohang. Analytical model well simulated the actual behavior of the piloti-type buildings during the earthquake. Analysis results showed that walls have an insufficient shear strength wherever the location of the staircase is and columns with insufficient transverse reinforcement could be failed when the staircase is located at a corner. Conclusively, structural engineers should design columns and walls in piloti-type buildings to possess sufficient capacity according to the location of staircase.

Validation of GenEcAm Software Results in Simulation of Seismic Behavior of Buildings Equipped with Damping System

This paper presents the validation process of the GenEcAm program made by the author by comparing the results obtained with this program with the results obtained with the SAP2000 program at the dynamic analysis of a P+10E building equipped with viscous fluid dampers, one on each facade on each level. The results obtained with these two programs are very close, which validates the correctness of the analytical and computational model that underpinned the creation of the GenEcAm program. The GenEcAm program allows the use of 9 theoretical models of hysteresis to simulate seismic behavior of the dampers that equippe the structure of a building.