• Earthquakes and Structures
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• v.13 no.3
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• pp.221-230
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• 2017

One of the important phases of probabilistic performance-based methodology is establishing appropriate probabilistic seismic demand models (PSDMs). These demand models relate ground motion intensity measures (IMs) to demand measures (DMs). The objective of this paper is selection of the optimal IMs in probabilistic seismic demand analysis (PSDA) of the RC high-rise buildings. In selection process features such as: efficiency, practically, proficiency and sufficiency are considered. RC high-rise buildings with core wall structural system are selected as a case study building class with the three characteristic heights: 20-storey, 30-storey and 40-storey. In order to determine the most optimal IMs, 720 nonlinear time-history analyses are conducted for 60 ground motion records with a wide range of magnitudes and distances to source, and for various soil types, thus taking into account uncertainties during ground motion selection. The non-linear 3D models of the case study buildings are constructed. A detailed regression analysis and statistical processing of results are performed and appropriate PSDMs for the RC high-rise building are derived. Analyzing a large number of results it are adopted conclusions on the optimality of individual ground motion IMs for the RC high-rise building.

• Earthquakes and Structures
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• v.15 no.4
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• pp.383-393
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• 2018

In this study, seismic performance of low and medium-rise RC buildings with wide-beam and ribbed-slab were evaluated numerically. Moment resisting systems consisting of moment and dual frame were selected as structural system of the buildings. Sufficiency of moment resisting wide-beam frames designed with high ductility requirements were evaluated. Upon necessity frames were stiffen with shear-walls. The buildings were designed in accordance with the Turkish Earthquake Code (TEC 2007) and were evaluated by using the strain-based nonlinear static method specified in TEC. Second order (P-delta) effects on the lateral load capacity of the buildings were also assessed in the study. The results indicated that the predicted seismic performances were achieved for the low-rise (4-story) building with the high ductility requirements. However, the moment resisting frame with high ductility was not adequate for the medium-rise building. Addition of sufficient amount of shear-walls to the system proved to be efficient way of providing the target performance of structure.

• Earthquakes and Structures
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• v.15 no.4
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• pp.443-452
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• 2018

In this paper the new intensity measures (IMs) for probabilistic seismic analysis of RC high-rise buildings with core wall structural system are proposed. The existing IMs are analysed and the new optimal ones are presented. The newly proposed IMs are based on the existing ones which: 1) comprise a wider range of frequency velocity spectrum content and 2) are defined as the integral along the velocity spectrum. In analysis characteristics of optimal IMs such as: efficiency, practicality, proficiency and sufficiency are considered. As prototype buildings, RC high-rise buildings with core wall structural system and with characteristic heights: 20-storey, 30-storey and 40-storey, are selected. The non-linear 3D models of the prototype buildings are constructed. 720 non-linear time-history analyses are conducted for 60 ground motion records with a wide range of magnitudes, distances to source and various soil types. Statistical processing of results and detailed regression analysis are performed and appropriate demand models which relate IMs to demand measures (DMs), are obtained. The conducted analysis has shown that the newly proposed IMs can efficiently predict the DMs with minimum dispersion and satisfactory practicality as compared to the other commonly used IMs (e.g., PGA and $S_a(T_1)$). The newly proposed IMs overcome difficulties in calculating of integral along the velocity spectrum and present adequate replacement for IMs which comprise a wider range of frequency velocity spectrum content.

• International Journal of High-Rise Buildings
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• v.3 no.2
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• pp.107-120
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• 2014

A Reinforced concrete (RC) shear wall system with coupling beams has been known as one of the most promising structural systems for high-rise buildings. However, significantly large flexural and/or shear stress demands induced in the coupling beams require special reinforcement details to avoid their undesirable brittle failure. In order to solve this problem, one of promising candidates is frictional hysteretic energy dissipating devices (HEDDs) as an alternative to the coupling beams. The introduction of frictional HEDDs into a RC shear wall system increases energy dissipation capacity and maintains the frame action after their yielding. This paper investigates the strength demands (specifically yield strength levels) with a maximum allowable ductility of frictional HEDDs based on comparative non-linear time-history analyses of a prototype RC shear wall system with traditional RC coupling beams and frictional HEDDs. Analysis results show that the RC shear wall systems coupled by frictional HEDDs with more than 50% yield strength of the RC coupling beams present better seismic performance compared to the RC shear wall systems with traditional RC coupling beams. This is due to the increased seismic energy dissipation capacity of the frictional HEDD. Also, it is found from the analysis results that the maximum allowable ductility demand of a frictional HEDD should increase as its yield strength decreases.

• International Journal of High-Rise Buildings
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• v.9 no.4
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• pp.315-323
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• 2020

In June 2016, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) in Japan delivered countermeasures against long-period ground motions caused by strong earthquakes along the Nankai trough. However, the countermeasures do not cover high-rise buildings equal to or shorter than 60 m in height, which do not require earthquake response analyses in the seismic design. Hence, in the present study, earthquake response analyses for such high-rise reinforced concrete (RC) buildings were performed under artificial ground motions assumed in the OS1 and OS2 regions to determine the base shear coefficients that satisfy a given safety demand. Furthermore, the results from the earthquake response analyses were estimated by the authors' proposed method based on the equivalent linearization method, showing good agreement and inspiring suggestions for more accurate and simplified estimations.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.241-244
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• 2008

The authors proposed a new rapid-screening method for more reasonably evaluating seismic capacities of medium and low-rise RC buildings controlled by both shear and flexure in Ref. [1]. The method proposed in Ref. [1] was based on relationships between required strengths of each failure system for ductility factors and damage degrees of overall system derived from the view-point of ductility factors. The proposed method was also verified using observed real damage data of low-rise RC buildings caused by past earthquakes. Results indicated that the methodology proposed in Ref. [1] compares well with real damages and is a useful strategy for rapidly identifying low-rise RC buildings having high potential seismic risk. In this study, in order to verify the applicability of the new methodology proposed in Ref. [1] to real RC building systems, seismic capacities of existing eleven low-rise RC buildings in Korea are evaluated based on the new method.

• Earthquakes and Structures
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• v.22 no.6
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• pp.625-635
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• 2022

High-rise buildings (HRBs) are considered one of the most common structures nowadays due to the population growth, especially in crowded towns. The lack of land in crowded cities has led to the convergence of the HRBs and the absence of any gaps between them, especially in lands with weak soil (e.g., liquefaction-prone soil), but then during earthquakes, these structures may be exposed to the risk of collision between them due to the large increase in the horizontal displacements, which may be destructive in some cases to the one or both of these adjacent buildings. To evaluate methods of reducing the risk of collision between adjacent twin HRBs, this research investigates three vibration control methods to reduce the risk of collision due to five different earthquakes for the case of two adjacent reinforced concrete (RC) twin high-rise buildings of 15 floors height without gap distance between them, founded on raft foundation supported on piles inside a liquefaction-prone soil. Contact pounding elements between the two buildings (distributed at all floor levels and at the raft foundation level) are used to make the impact strength between the two buildings realistic. The mitigation methods investigated are the base isolation, the tuned mass damper (TMD) method (using traditional TMDs), and the pounding tuned mass damper (PTMD) method (using PTMDs connected between the two buildings). The results show that the PTMD method between the two adjacent RC twin high-rise buildings is more efficient than the other two methods in mitigating the earthquake-induced pounding risk.

• Earthquakes and Structures
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• v.11 no.3
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• pp.483-503
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• 2016

This study aims to evaluate seismic performance of existing low and mid-rise reinforced concrete buildings by comparing their displacement capacities and displacement demands under selected ground motions experienced in Turkey as well as demand spectrum provided in 2007 Turkish Earthquake Code for design earthquake with 10% probability of exceedance in 50 years for soil class Z3. It should be noted that typical residential buildings are designed according to demand spectrum of 10% probability of exceedance in 50 years. Three RC building sets as 2-, 4- and 7-story, are selected to represent reference low-and mid-rise buildings located in the high seismicity region of Turkey. The selected buildings are typical beam-column RC frame buildings with no shear walls. The outcomes of detailed field and archive investigation including approximately 500 real residential RC buildings established building models to reflect existing building stock. Total of 72 3-D building models are constructed from the reference buildings to include the effects of some properties such as structural irregularities, concrete strength, seismic codes, structural deficiencies, transverse reinforcement detailing, and number of story on seismic performance of low and mid-rise RC buildings. Capacity curves of building sets are obtained by nonlinear static analyses conducted in two principal directions, resulting in 144 models. The inelastic dynamic characteristics are represented by "equivalent" Single-Degree-of- Freedom (ESDOF) systems using obtained capacity curves of buildings. Nonlinear time history analysis is used to estimate displacement demands of representative building models idealized with (ESDOF) systems subjected to the selected ground motion records from past earthquakes in Turkey. The results show that the significant number of pre-modern code 4- and 7-story buildings exceeds LS performance level while the modern code 4- and 7-story buildings have better performances. The findings obviously indicate the existence of destructive earthquakes especially for 4- and 7-story buildings. Significant improvements in the performance of the buildings per modern code are also obvious in the study. Almost one third of pre-modern code buildings is exceeding LS level during records in the past earthquakes. This observation also supports the building damages experienced in the past earthquake events in Turkey.

• Journal of Korean Association for Spatial Structures
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• v.22 no.4
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• pp.71-79
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• 2022

Recently, the construction of tall buildings utilized by high strength-concrete in the whole world is tending to be on the rise. The application of high-rise structural system in buildings results in the excellent cut-down effect in construction materials due to section reduction. Therefore, in order to investigate the CO₂ and resource reduction effect for the high-rise structural system, comparisons of GWP and ADP in embodied energy of structural materlais between 4 type of high-rise structural system have been performed. As a result, GWP emission increased in the order of steel structure outrigger system, RC shear wall system, and RC outrigger system. On the other hand, ADP emissions increased in the order of RC shear wall system, RC outrigger system, and steel structure outrigger system.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.191-195
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• 1992

Optimization of the RC pile cap for high rise apartment building has been performed with the aim of the cost minimization. The principle of divided parameters has been used. As a result the cost has been reduced by 25percentage.