International Journal of Earth Sciences and Engineering

Bharat Singh Chauhan ¹, Ashok Kumar Ahuja ¹

Affiliations
1 Department of Civil Engineering, Indian Institute of Technology, Roorkee-247667, Uttarakhand, IN

Abstract

This research paper investigates the modification of wind loads on a tall building (principal building) having rectangular cross-sectional shape due to the variation in height of two closely located interfering buildings having a similar plan shape. The models of the three buildings (principal and interfering buildings) are placed in a U shape plan for the study. The heights of interfering building models are varied in two different manners: (1). Height of both the interfering building models is reduced simultaneously (2). Height of only one of the interfering building model is reduced. Wind tunnel experiments are undertaken using five component force balance load cell and the results are reported in the form of X-Y plots. The interference effect causes increase in the torsional moment as height difference of the two interfering buildings increase, also shielding effect causes reduction in the along wind force as height of the interfering buildings increases. Value of torsion on the principal building is observed to be as high as 33 times of that in the isolated case. However, a reduction is high as 69 percent is observed in the force in along wind direction due to shielding.

Keywords

Wind Tunnel, Tall Building, Rectangular Plan, Interference Effects, Height Variation, U-Shape, Force Measurement.

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Gudeta Konkone Bekele ¹, Ashok Kumar Ahuja ¹

Affiliations
1 Department of Civil Engineering, Indian Institute of Technology, Roorkee-247667, Uttarakhand, IN

Abstract

Industrial buildings are generally provided with sloping roofs with the provision of the entry of natural light through it. Sky light roof is one of such roofs. The information available in the literature regarding wind pressure distribution on sky light roof is limited. An effort has, therefore, been made to carry out an experimental study on the model of low-rise building with Sky light roof in order to generate more information about wind pressure distribution on it. Inflexible model of the rectangular plan low-rise building is made of Perspex sheet. It is provided with many pressure points on the upper surface of the roof. The model is tested in an open circuit boundary layer wind tunnel to measure values of wind pressures at all pressure points. Wind is made to hit the model at seven wind frequency edges from 0° to 90° at an interim of 15°. Values of mean wind pressure coefficients are evaluated from the measured values of wind pressures and contours are plotted. Values of mean wind pressure coefficients obtained experimentally are also compared with those available in the literature.

Keywords

Wind Pressure Coefficient, Sky Light Roof, Low-Rise Building, Wind Incidence Angle.

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Adal Mengesha Yimer ¹, Ashok Kumar Ahuja ²

Affiliations
1 Structural Engineering, IIT Roorkee, Roorkee-247667, Uttarakhand, IN
2 Wind Engineering, IIT Roorkee, Roorkee-247667, Uttarakhand, IN

Abstract

Tall buildings have been traditionally designed to be symmetric rectangular, square, triangular as well as circular in plan, in order to avoid excessive seismic-induced torsional vibrations due to eccentricity, in seismic-prone and highly wind induced regions. But, due to architectural and structural requirements, complicated tall and slender buildings with various corner configuration and cross-sectional shapes are emerged now a day, which are difficult to design using the existing wind load standards only. The principal aim of this study is to investigate the effect of chamfered edged configuration on wind pressure distribution on tall buildings experimentally using open circuit wind tunnel. The test is conducted under a mean wind velocity profile of approaching flow 9.61 m/sec. A total of 2 rigid Perspex sheet models of equal height are prepared at scale of 1:100, for this study, one with rectangular cross-section and another with chamfered vertical edges. Wind pressure values at many pressure points on the model wall surfaces are measured and wind pressure coefficients are calculated under varying wind incidence angles from 0° to 90° for rectangular shape and from 0° to 180° for chamfered edges at 30° interval. The surface and cross sectional variations of mean pressure coefficient are presented in this paper. From this study, it is observed that chamfering vertical edges and wind incidence angle have great effect in altering wind load magnitude.

Keywords

Rigid Model, Corner Configuration, Velocity Profile, Pressure Coefficient.

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