• 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.

• International Journal of High-Rise Buildings
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• v.2 no.3
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• pp.245-255
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• 2013

This paper presents the results of a set of wind tunnel tests carried out to examine wind-induced overall structural loads on rectangular medium-rise buildings. Emphasis was directed towards torsion and its correlation with peak shear forces in transverse and longitudinal directions. Two building models with the same horizontal dimensions but different gabled-roof angles ($0^{\circ}C$ and $45^{\circ}C$) were tested at different full-scale equivalent eave heights (20, 30, 40, 50, and 60 m) in open terrain exposure for all wind directions (every $15^{\circ}C$). Wind-induced pressures were integrated over building surfaces and results were obtained for along-wind force, across-wind force, and torsional moment. Maximum wind force component was given along with the other simultaneously-observed wind force components normalized by the overall peak. The study found that for flat-roofed buildings maximum torsion for winds in transverse direction is associated with 80% of the overall shear force perpendicular to the longer horizontal building dimension; and 45% of the maximum shear occurs perpendicular to the smaller horizontal building dimension. Comparison of the wind tunnel results with current torsion provisions in the American wind standard, the Canadian and European wind codes demonstrate significant discrepancies. Suggested load combination factors were introduced aiming at an adequate evaluation of wind load effects on rectangular medium-rise buildings.

• Wind and Structures
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• v.27 no.6
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• pp.439-449
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• 2018

Wind loading of a tall building built amidst a group of buildings in urban environment is always greatly affected by shielding effects. Wind tunnel tests were carried out to assess the shielding provided by a row of low-rise or medium-rise buildings upstream a square-section tall building of height-to-breadth ratio 6. Mean and dynamic wind loads on the tall building were measured at different wind incidence angles and presented as interference factors (IFs). It is found that presence of a row of upstream buildings provides significant shielding to the tall building. At normal wind incidence, the mean along-wind loads and all components of fluctuating wind loads on the tall building are always reduced by shielding. Vortex shedding seems to still occur on the upper exposed part of the tall building but the vortex excitation levels are largely reduced. The degree of shielding is found to depend on a number of arrangement parameters of the row of upstream buildings. Empirical equations are proposed to quantify the shielding effect based on the wind tunnel data.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.465-472
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• 2000

Seismic isolation technique has been applied mainly in low rise buildings and its seismic performance was satisfactory during Kobe Earthquake. However, in the case of medium and/or high-rise buildings, mid-story isolation could be more technically feasible than base isolation to reduce earthquake forces. In this paper, the seismic effectiveness of mid-story isolation in medium and/or high-rise shear building as well as low rise shear building was evaluated analytically. After verifying the effectiveness of mid-story isolation technique, this method also applied in residential-commercial building. It was found that mid-story isolation, that is isolation between upper residential area and lower commercial area, could reduce inter-story drift and floor shear forces comparing to the conventional fixed base.

• Wind and Structures
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• v.15 no.5
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• pp.423-439
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• 2012

Three common medium- rise building forms were physically tested to study their overall wind induced structural response. Emphasis was placed on the torsional response and its correlation with other peak responses. A higher correlation was found between the peak responses than between the general fluctuating parts of the signals. This suggests a common mechanism causing the peak event, and that this mechanism is potentially different to the mechanism causing the general load fluctuations. The measurements show that about 80% of the peak overall torsion occur simultaneously with the peak overall along wind drag for some generic building shapes. However, the peak torsional response occurs simultaneously with only 30%-40% of the peak overall drag for the rectangular model. These results emphasise the importance of load combinations for building design, which are often neglected in the design of medium sized rigid buildings for which the along-wind drag is dominant. Current design wind loading standards from around the world were evaluated against the results to establish their adequacy for building design incorporating wind-induced torsion effects. Although torsion is frequently neglected, for some structural systems it may become more important.

• Wind and Structures
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• v.13 no.5
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• pp.433-449
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• 2010

Wind tunnel model tests were conducted for a residential apartment block located within the complex terrain of The Hong Kong University of Science and Technology (HKUST). The test building is typical of medium-rise residential buildings in Hong Kong. The model study was conducted using modelling techniques and assumptions that are commonly used to predict design wind loads and pressures for buildings sited in regions of significant topography. Results for the building model with and without the surrounding topography were compared to investigate the effects of far-field and near-field topography on wind characteristics at the test building site and wind-induced external pressure coefficients at key locations on the building facade. The study also compared the wind tunnel test results to topographic multipliers and external pressure coefficients determined from nine international design standards. Differences between the external pressure coefficients stipulated in the various standards will be exacerbated when they are combined with the respective topographic multipliers.

• Earthquakes and Structures
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• v.11 no.5
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• pp.741-777
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• 2016

A simplified approach of assessing torsionally balanced (TB) and torsionally unbalanced (TU) low-medium rise buildings of up to 30 m in height is presented in this paper for regions of low-to-moderate seismicity. The Generalised Force Method of Analysis for TB buildings which is illustrated in the early part of the paper involves calculation of the deflection profile of the building in a 2D analysis in order that a capacity diagram can be constructed to intercept with the acceleration-displacement response spectrum diagram representing seismic actions. This approach of calculation on the planar model of a building which involves applying lateral forces to the building (waiving away the need of a dynamic analysis and yet obtaining similar results) has been adapted for determining the deflection behaviour of a TU building in the later part of the paper. Another key original contribution to knowledge is taking into account the strong dependence of the torsional response behaviour of the building on the periodic properties of the applied excitations in relation to the natural periods of vibration of the building. Many of the trends presented are not reflected in provisions of major codes of practices for the seismic design of buildings. The deflection behaviour of the building in response to displacement controlled (DC) excitations is in stark contrast to behaviour in acceleration controlled (AC), or velocity controlled (VC), conditions, and is much easier to generalise. Although DC conditions are rare with buildings not exceeding 30 m in height displacement estimates based on such conditions can be taken as upper bound estimates in order that a conservative prediction of the displacement profile at the edge of a TU building can be obtained conveniently by the use of a constant amplification factor to scale results from planar analysis.

• International Journal of High-Rise Buildings
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• v.11 no.3
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• pp.171-180
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• 2022

Research and development on high-rise or large-scale wooden buildings have been actively conducted both domestically and internationally. The trend of high-rise wooden buildings is driven by increasing awareness of environmental issues. To utilize wooden materials in buildings is believed to lead to the reduction of the environmental impact. On the other hand, Japan is one of the most earthquake-prone countries in the world, and many wooden detached houses have been damaged in past major earthquakes. This paper summarizes the issues that arise in the realization of medium- and high-rise wooden buildings in Japan, and introduces the initiatives that have been seen so far.

• Journal of Korean Association for Spatial Structures
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• v.7 no.4
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• pp.97-104
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• 2007

This paper is concerned with the vibration characteristics of medium-rise building, which severely vibrated by vehicles. The field vibration measurement was employed for finding the vibration source and vibration reducing method. Time domain data from measurements were also utilized for vibration characteristics, such as effect of buses and subways-induced vibration on the floor vibration of the building. effectiveness of the vibration reducing method was also demonstrated.

• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.55-62
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• 2011

While frequency of occurrence of terrorism has recently increased, it intensively occurs in buildings that many unspecified persons gather. Terrorism which occurs in high-rise buildings causes a lot of damage. It is necessary for design approach to reduce terrorism damage from explosive of buildings. Terror risk analysis of domestic tall and high-rise buildings is evaluated by fema 455, Rapid Visual Screening which is found to be comparatively simple and practicable. Common risk factors of terrorism in domestic buildings were investigated. The results of terror risk assessment of all buildings are found to be a medium risk score, Main reason is that domestic tall or high-rise buildings have similar external-environmental factors.