Jordan Journal of Civil Engineering, Volume 8, No. 3, 2014 - 251 - © 2014 JUST. All Rights Reserved. Experimental Investigation of Surface Pressure on ‘+’ Plan Shape Tall Building Souvik Chakraborty 1) , Sujit Kumar Dalui 2) and Ashok Kumar Ahuja 3) 1) Post Graduate Student, Department of Civil Engineering, Bengal Engineering and Science University, Shibpur, Howrah, India 2) Assistant Professor, Department of Civil Engineering, Bengal Engineering and Science University, Shibpur, Howrah, India 3) Professor, Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee, India E-Mails: csouvik41@gmail.com (S.Chakraborty), sujit_dalui@rediffmail.com (S.K. Dalui) ABSTRACT The variation in pressure distribution with change in wind orientation angle on different faces of a ‘+’ plan shape tall building is studied in this paper. Experiments have been carried out with a rigid model in a boundary layer wind tunnel for wind incidence angles of 0˚ and 45˚. Peculiar pressure distributions on certain faces are observed. Moreover, drastic change in pressure distribution is observed for the two wind angles. Finally, the flow pattern around the model is computed using Computational Fluid Dynamics (CFD) package ANSYS CFX in order to explain the variation in pressure on different faces. KEYWORDS: Wind tunnel testing, Interference effect, Mean pressure coefficient, Tall building, Wind incidence angle, Vortex shedding. INTRODUCTION Wind engineering is a wide ranging multi- disciplinary subject that has developed over the last few decades and is concerned with the effects of wind on the natural and built environment. These effects can be catastrophic, leading to the failure of major buildings or other structures or can lead to discomfort and disruption. Shortage of land around the world has given rise to construction of tall structures. Generally, these buildings are susceptible to wind load. The risk regarding wind load is even more for irregular plan shape buildings. Irregular flow around the building gives rise to dynamic behaviour of wind resulting from phenomena such as vortex shedding, buffering, galloping and flutter. Change in wind incidence angle may also lead to dynamic behaviour of wind. Although guidelines regarding pressure coefficients on regular plan shape buildings are available in international standards, viz. IS: 875 (part3) – 1987, AS/NZS: 1170.2 (2002), ASCE: 7-02 (2002), NBC (Part 4) (1995), the standards are mum regarding irregular plan shape buildings. Under wind action, a structure experiences two forces, viz. drag and lift. While drag gives rise to positive pressure, negative pressure (suction) is generated by lift. Fair amount of research have already been carried out regarding tall buildings. Hayashida et al. (1990) studied the effect of different building plan shapes on aerodynamic force and displacement response of super high rise buildings. Davenport (1993) investigated the response of slender buildings when subjected to wind load. Thepmongkorn et al. (2002) studied the interference effect on wind induced coupled translational- torsional motion of tall buildings. The results indicated a significant increase in responses at Accepted for Publication on 16/2/2014.