INFLUENCE OF VARIOUS PARAMETERS ON MEAN WIND PRESSURE DISTRIBUTION ON SLOPING ROOFS

Abstract

It has been identified that there exists a serious lack of observation and research facilities for collection of necessary data to design engineet.ing structures against wind forces. This is particularly true for India and other developing countries. In India, almost every year many buildings, electrical transmission towers and other tall structures suffer damage due to wind storms and upset the power and communication facilities affecting production besides loss of human lives. In the design and analysis of a variety of structures constructed on the earth's surface, wind loads have also to be considered. Evaluation of design wind loads on structures require information on design wind speed and pressure or force coefficients besides other parameters. Understanding of the wind effects on structures has not reached the stage where a designer can use the available information with reasonable degree of confidence for many situations. The available information is also insufficient to develop analytical and numerical methods which can be used for understanding wind effects on civil engineering structures. As such, there still exists considerable need for making experimental analysis to understand the effects of wind on structures. (vill) Where as flat roofs are generally used for residential buildings, sloping roofs are employed for both residential and industrial buildings due to its advantages namely easy drainage of rain water and snow, and availability of large column free area. Sloping roofs in case of industrial buildings require entry of natural light through its roof surfaces. North light or saw-tooth and sloping roofs with sky light are solution to this need. An overall review of literature indicates that information regarding wind loads on flat and pitched roofs of common shape is available in most of the codes of practices and literature, whereas such information on sloping roofs with sky light is limited. The most common technique for making experimental investigations of wind effects on structures is by means of models, tested in a wind tunnel under simulated field conditions. In the present study of wind loads on sloping roofs with sky light, six rigid models are made and are tested in order to study the influence of various structural and flow parameters namely wind incidence angle, terrain roughness, roof slope, model scale and permeability, on pressure coefficients. Local and average values of pressure coefficients are obtained from the measured values of wind pressure and presented in the form of tables and figures......