• Earthquakes and Structures
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• v.16 no.4
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• pp.401-413
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• 2019

The concept of base isolation for equipment is well known. Its application in buildings and structures is rather challenging. Introduction of horizontal flexibility at the base helps in proper energy dissipation at the base level thus reducing the seismic demand of the super structure to be considered during design. The present study shows the results of a series of numerical simulation studies on seismic responses of secondary system (SS) housed in non-isolated and base-isolated primary structures (PS) including equipment-structure interactions. For this study the primary structure consists of two similar single bay three-store reinforced cement concrete (RCC) Frame building, one non-isolated with conventional foundation and another base isolated with Lead plug bearings (LPB) constructed at IIT Guwahati, while the secondary system is modeled as a steel frame. Time period of the base isolated building is higher than the fixed building. Due to the presence of isolator, Acceleration response is significantly reduced in both (X and Y) direction of Building. It have been found that when compared to fixed base building, the base isolated building gives better performance in high seismic prone areas.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.239-249
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• 2002

The Turbine Building of nuclear power plant is classified as non safety-related structure. During the operation, there may be possibility the original licensing basis would be changed, which makes non safety-related structure safety-related. Such a change in regulation requires utility to perform seismic qualification for the existing structure and their facilities. Thus it is meaningful to evaluate seismic margin of the existing non-qualified building structure. In addition, in this paper it is shown that a modification to the structure can enhance their seismic capacity.

• Structural Engineering and Mechanics
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• v.73 no.1
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• pp.53-64
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• 2020

In different high seismic regions around the world, many non-ductile existing reinforced concrete frame buildings, built without adequate seismic detailing requirements, have been damaged or collapsed after past earthquakes. The assessment and the retrofit of these non-ductile concrete structures is crucial theme of research for all the scientific community of engineers. In particular, a careful assessment of the existing building is fundamental for understanding the failure mechanisms that govern the collapse of the structure or the achievement of the recommended limit states. Based on the seismic assessment, the best retrofit strategy can be designed and applied to the structure. A school building located in Avellino province (Italy) is the case study. The analysis of seismic vulnerability carried out on the mentioned building has highlighted deficiencies in both static and seismic load conditions. The retrofit of the building has been designed based on different retrofit options in order to show the real retrofit design developed from the engineers to achieve the seismic safety of the building. The retrofit costs associated to structural operations are calculated for each case and have been summed up to the costs of the in situ tests. The paper shows a real retrofit design case study in which the best solution is chosen based on the results in terms of structural performance and cost among the different retrofit options.

• Structural Engineering and Mechanics
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• v.37 no.2
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• pp.233-251
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• 2011

The seismic provisions of the current edition (2005) of the National Building Code of Canada (NBCC) differ significantly from the earlier edition. The current seismic provisions are based on the uniform hazard spectra corresponding to 2% probability of exceedance in 50 years, as opposed to the seismic hazard level with 10% probablity of exeedance in 50 years used in the earlier edition. Moreover, the current code is presented in an objective-based format where the design is performed based on an acceptable solution. In the light of these changes, an assessment of the expected performance of the buildings designed according to the requirements of the current edition of NBCC would be very useful. In this paper, the seismic performance of a set of six, twelve, and eighteen story buildings of regular geometry and with concrete moment resisting frames, designed for Vancouver western Canada, has been evaluated. Although the effects of non-structural elements are not considered in the design, the non-structural elements connected to the lateral load resisting systems affect the seismic performance of a building. To simulate the non-structural elements, infill panels are included in some frame models. Spectrum compatible artificial ground motion records and scaled actual accelerograms have been used for evaluating the dynamic response. The performance has been evaluated for each building under various levels of seismic hazard with different probabilities of exceedance. From the study it has been observed that, although all the buildings achieved the life-safety performance as assumed in the design provisions of the building code, their performance characteristics are found to be non-uniform.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.6
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• pp.267-275
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• 2020

In the event of an earthquake, non-structural components require seismic performance to ensure evacuation routes and to protect lives from falling non-structural components. Accordingly, the seismic design code proposes horizontal force for the design and evaluation of non-structural components. Ground motion observed on each floor is affected by a building's eigen vibration mode. Therefore, the earthquake damage of non-structural components is determined by the characteristics of the non-structural component system and the vibration characteristics of the building. Floor response spectra in the seismic design code are estimated through time history analysis using seismic waves. However, it is difficult to use floor response spectra as a design criterion because of user-specific uncertainties of time history analysis. In addition, considering the response characteristics of high-rise buildings to long-period ground motions, the safety factor of the proposed horizontal force may be low. Therefore, this study carried out the horizontal force review proposed in the seismic design code through dynamic analysis and evaluated the floor response of seismic waves considering buildings and predominant periods of seismic waves.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.6
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• pp.253-263
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• 2023

Non-structural elements, such as equipment, are typically affixed to a building's floor or ceiling and move in tandem with the structure during an earthquake. Seismic forces acting upon non-structural elements traverse the ground and the building's structure. Considering this seismic load transmission mechanism, it becomes imperative to account for the interactions between soil, structure, and equipment, establishing seismic design procedures accordingly. In this study, a Soil-Structure-Equipment Interaction (SSEI) model is developed. Through seismic response analysis using this model, how the presence or absence of SSEI impacts equipment behavior is examined. Neglecting the SSEI aspect when assessing equipment responses results in an overly conservative evaluation of its seismic response. This emphasizes the necessity of proposing an analytical model and design methodology that adequately incorporate the interaction effect. Doing so enables the calculation of rational seismic forces and facilitates the seismic design of non-structural elements.

• Structural Engineering and Mechanics
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• v.53 no.4
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• pp.791-818
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• 2015

RC buildings constitute the prevailing type of construction in earthquake-prone region like Kathmandu Valley. Most of these building constructions were based on conventional methods. In this context, the present paper studied the seismic behaviour of existing RC buildings in Kathmandu Valley. For this, four representative building structures with different design and construction, namely a building: (a) representing the non-engineered construction (RC1 and RC2) and (b) engineered construction (RC3 and RC4) has been selected for analysis. The dynamic properties of the case study building models are analyzed and the corresponding interaction with seismic action is studied by means of non-linear analyses. The structural response measures such as capacity curve, inter-storey drift and the effect of geometric non-linearities are evaluated for the two orthogonal directions. The effect of plan and vertical irregularity on the performance of the structures was studied by comparing the results of two engineered buildings. This was achieved through non-linear dynamic analysis with a synthetic earthquake subjected to X, Y and $45^{\circ}$ loading directions. The nature of the capacity curve represents the strong impact of the P-delta effect, leading to a reduction of the global lateral stiffness and reducing the strength of the structure. The non-engineered structures experience inter-storey drift demands higher than the engineered building models. Moreover, these buildings have very low lateral resistant, lesser the stiffness and limited ductility. Finally, a seismic safety assessment is performed based on the proposed drift limits. Result indicates that most of the existing buildings in Nepal exhibit inadequate seismic performance.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.4
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• pp.161-168
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• 2021

Existing old reinforced concrete buildings could be vulnerable to earthquakes because they were constructed without satisfying seismic design and detail requirements. In current seismic design standards, the target collapse probability for a given Maximum Considered Earthquake (MCE) ground-shaking hazard is defined as 10% for ordinary buildings. This study aims to estimate the collapse probabilities of a three-story, old, reinforced concrete building designed by only considering gravity loads. Four different seismic design categories (SDC), A, B, C, and D, are considered. This study reveals that the RC building located in the SDC A region satisfies the target collapse probability. However, buildings located in SDC B, C, and D regions do not meet the target collapse probability. Since the degree of exceedance of the target probability increases with an increase in the SDC level, it is imminent to retrofit non-ductile RC buildings similar to the model building. It can be confirmed that repair and reinforcement of old reinforced concrete buildings are required.

• Computers and Concrete
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• v.8 no.6
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• pp.693-715
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• 2011

The main object of this study is to evaluate the seismic response effects on a reinforced concrete building isolated by triple concave friction pendulum (TCFP) bearings. The site-response effects arise from the difference in the local soil conditions at the support points of the buildings. The local soil conditions are, therefore, considered as soft, medium and firm; separately. The results on the responses of the isolated building are compared with those of the non-isolated. The building model used in the time history analysis, which is a two-dimensional and eight-storey reinforced concrete building with and without the seismic isolation bearings and/or the local soil conditions, is composed of two-dimensional moment resisting frames for superstructure and of plane elements featuring plane-stress for substructure. The TCFP bearings for isolating the building are modelled as of a series arrangement of the three single concave friction pendulum (SCFP) bearings. In order to investigate the efficiency of both the seismic isolation bearings and the site-response effects on the buildings, the time history analyses are elaborately conducted. It is noted that the site-response effects are important for the isolated building constructed on soft, medium or firm type local foundation soil. The results of the analysis demonstrate that the site-response has significant effects on the response values of the structure-seismic isolation-foundation soil system.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.4
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• pp.235-244
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• 2018

The main function of the general hospital building is to provide medical facilities and service. However, damage to the non-structural elements such as architectural, medical, mechanical and other components will interrupt those functions after the earthquake. Especially, it is considered that, damage to the non-structural elements is a serious event because it is directly associated with the lives of patients. Therefore, this study evaluated whether the certain non-structural elements of general hospital building has the seismic performance to provide hospital medical services after the earthquake. The evaluation is conducted by selecting the non-structural elements used in general hospital which are sensitive to acceleration, such as cooling towers, air handler, MRI and CT. As a result, the non-structural elements located on the upper floor without suitable support method did not meet the performance objective. Therefore, adequate anchorage against the seismic event is required for such non-structural elements that are acceleration-sensitives.