Determination of the Drag Force Disturbance Index for Analysis of the Neighborhood Effect in Tall Buildings Subject to Wind

Resumo

The presence of obstacles around a building can interfere with wind flow, modifying the pressures on the facades and, consequently, the resulting forces and moments. These interferences can generate protective effects or increase pressure coefficients. Therefore, it is important to study wind behavior in buildings in the presence of neighbors to better understand these effects and ensure the safety of structures. Most physical phenomena cannot be predicted with complete certainty and repeated measurements of these phenomena generate random results, with some of these results being more frequent than others. Reliability analyzes are commonly used to examine the behavior of structures subjected to such phenomena, and one of these analyzes is considering the beta reliability index, which has several representations and in this case, the determination of beta is proposed, not being considered a criterion of failure, but rather as a change in the state of the drag force. In this sense, the present work presents the determination, through reliability, of the drag force disturbance index, that is, how much the drag force is being modified depending on the presence of the neighbor, in order to evaluate the behavior of the effects of the wind from the CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building model, using experimental data generated in a wind tunnel. The standard tall building model was studied in different positions, subjected to variable drag force actions, in isolation and with the existence of different neighborhoods. Probabilistic concepts and graphs of results are presented and discussed in relation to the directions adopted by CAARC for beta variation indices. With the results found, it was observed that the existence of a neighborhood affects the average values of the data, as well as the aforementioned index, both for increase and reduction compared to the isolated building, depending on the situation. Therefore, this study presents interpretations that can help predict the behavior of tall buildings subjected to wind loads in the presence of neighborhoods.