No abstract

Roof shape and slope are both important parameters for the safety of a structure, especially when facing wind loads. The present study demonstrates the pressure variations due to wind load on the pyramidal roof of a square plan low-rise building with 15% wall openings through CFD (Computational Fluid Dynamics) simulation. Many studies on roofed structures have been performed in the past; however, a detailed review of the literature indicates that the majority of these studies focused on flat, hip, gable and spherical roofs only. There is a lack of research that analyses these effects on pyramidal roof buildings. ANSYS (Analysis System) ICEM (Integrated Computer Engineering and Manufacturing)-CFD and ANSYS Fluent commercial packages have been used for modelling and simulation, respectively, and ANSYS CFD Post was used to obtain the results. A realizable k-ε turbulent model was used for the pressure distribution on the roof of the building model. In the present study, twenty-four models with different roof slopes (α), i.e. 0°, 10°, 20°, and 30°, with various wind incidence angles (ϴ), i.e. 0°, 15°, 30°, 45°, 60° and 75° were investigated. The influence of roof slope and wind incidence angle are analysed in this study. Results have been represented through pressure coefficient (Cp) contours on the roof surface and velocity streamlines of the flow field of the different cases. The optimization of the roof slope may be achieved by considering different wind incidence angles for buildings so that they may better withstand wind force in a specific area. When wind pressure coefficients from building models with openings were compared with pressure coefficients from building models without openings, it was found that the pressure coefficients for building models without openings are almost twice or three times that of the pressure coefficients for models with openings.

For the structural safety to counter the wind load, the roof shape and the roof slope both the constraints play an important role. The present study demonstrates the pressure distribution on the pyramidal roofs of a pentagonal and hexagonal plan low-rise single-story building due to the wind load through CFD simulation. This type of roofed building may be considered as one of the cyclone shelters as it is shown by post-disaster studies that pyramidal roof is found better than other roof shapes to resist the wind load. The modeling of the building and the meshing of the models have been carried out in ANSYS ICEM CFD, while the simulation process has been performed in ANSYS Fluent. To obtain the results, ANSYS CFD-Post has been utilized. For the simulation of the turbulent wind flow, a realizable k-ε turbulent model is used in the present study. In the current study, ten different building models (five with pentagonal plan and five with hexagonal plan) are generated having roof angles 20°, 25°, 30°, 35° and 40°, and all are simulated for 0°-45° wind direction @15° interval. The pressure coefficient contours for different wind directions for varying roof slopes are mapped in the present study. Results show that the hexagonal pyramidal roof surface building has low-pressure coefficients and better chances of survival than the pentagonal pyramidal roof surface building.

The effect of pressure because of the winds on the exterior of gable roof of a low-rise single-storey building has been analyzed in present research using CFD simulation. Roof slope, which is most important factor for safety of structure was taken into consideration. Many past researchers have studied roofed structures but the majority of these researches have been carried on flat roofs, hip roof, spherical roofs, pyramidal roofs. There is need of researches that analyses effect of winds on gable roofs as these kinds of roofs are generally more susceptible to wind damage. ANSYS ICM is used for modeling and meshing and ANSYS Fluent for simulation. Results are extracted here using CFD post. In this very study three models with slope ang 10°, 20° and 30° with same incidence angle 0° were examined. This study analyses the effect of slope of the roof and angle of incidence of wind. The streamlines of velocity around the building model and pressure coefficient (Cp ) contours on the surfaces of the roof are opted here to represent the results. When results were plotted it was found that pressure coefficients were switching from negative to positive as the slope of the roof increases and the formation of vortex on leeward gets complicated as we go on increasing the slopes.