Performance of lightweight floor diaphragms under lateral loads

Abstract

Floor structural elements carry permanent and imposed loads applied to the floor to the surrounding beams, columns, or wall panels. Floor system transfers the load under bending type out-of-plane mode of deformation as well as distributes the resultant wind and earthquake actions to the lateral load resisting system under membrane-type in-plane deformations; the latter called diaphragm action. Floor diaphragms are often assumed to be rigid elements. This is a simplifying assumption in the analysis of the floor diaphragms; and while correct for many types of floors, can be too simplistic for lightweight systems such as those investigated in this study. Standards are silent on the rigidity of lightweight floors while the engineering community takes the rigidity of this type of floor for granted. This can potentially lead to the failure of structures at extreme load events. The poor design of floor systems has been the reason of various failures of the structures in the earthquakes such as Northridge earthquake, in 1994, in Southern California and Umbria-Marche earthquake in 1997. The current study is therefore proposed to investigate the behaviour of lightweight floors composed of timber joists and particle boards. Australia is at the forefront of using timber structures as low- and mid-rise residential and non-residential buildings. However, little attention has been paid to study the performance of lightweight-timber structures and timber floor diaphragms under wind and seismic loading. This research adds to the data available on the role of the floor diaphragm in distributing the lateral load and pushes the boundaries of the state of the art in particular in relation to the influence of cladding panels to bare-timber frame buildings in order to better understand the performance of structures and floor diaphragms at various stages of construction. The novelty of the research is also in considering the interaction between both floor diaphragm elements and lateral loading resisting systems to transfer the lateral cyclic loads by implementing full-scale experiments. Furthermore, the accurate evaluation of the performance of connections led to a valid numerical model which can be the reference for assessing the lightweight floor diaphragms. The results are useful for practicing engineers and researchers alike.

Date of Award	2022
Original language	English