Análise dinâmica de laje de ambiente de trabalho submetida a cargas de caminhada

Abstract

Excessive vibrations in civil structures have been studied along decades. From the 19th century to present days, the occurrences of such phenomenon have surprised both engineering professionals and users of affected structures (e.g.: bridges, footbridges, grandstands). This phenomenon can result in many negative consequences, such as: dissatisfaction of users, people’s feeling of insecurity; loss of productivity at a workplace; further economic losses; etc. From the 1950s and 1960s, cases involving excessive floor vibrations started being reported regularly and, up to date, research studies on these cases have been continuously published in the scientific literature. The dynamic behavior of office floors is a significant research theme, once floors are daily subjected to walking induced loads. Currently, criteria of design guides/standards recommend computational simulations of a single-walker excitation for verifying vibration serviceability of office floors. However, the recurrent number of excessive vibration cases leads to doubts the effectiveness of such recommendation. In this context, this work presents investigations on the dynamic behavior of a FEM (Finite Element Method) model of office floor subjected to walking loads in different scenarios of people’s transit. In these simulations, the walking load model expressed by the Fourier Series was used, with recommendations of the international standard ISO 10137. It was simulated resonant excitation scenarios with one person into walking activity, two people walking along the same trajectory, and two people walking along the different trajectories. Levels of synchronization between people’s walking excitations and time differences between walkers were considered. Results indicate that RMS acceleration values (measured at the center of the slab) of two-walker scenarios exceed, in most scenarios, those ones measured in one-walker scenarios, with significant percentage changes. Such fact suggests the need for considering different numbers of walker in normative reccomendations, aiming at contributing to more efficient structural design of office floors, in terms of prevention of excessive vibrations due to walking-induced excitation.