Influence of the opening on the vibration damage to masonry construction caused by construction activities

Abstract

Use of heavy construction machineries close to existing structures is complained for cracking of un-reinforced masonry structures. Domestic houses, which are built with un-reinforced masonry, are particularly vulnerable for cracking due to construction induced vibration. To limit the structural damage to masonry construction, Environmental Authority has come up with velocity 2mms-l and frequency range of (10-50) Hz as the safe vibration level for masonry constructions. However, complaints of damages to masonry structures still exist at these threshold levels. Apart from masonry type, vibration impact also depends on the number of openings, shape and size of the openings and the fixity condition of the wall panel. In this study, wall panels with different openings that have sustained damages at the threshold vibration level during the construction activities of Colombo — Matara express way are analysed to evaluate the relevance of current threshold limit and determine the influence of the opening on the dynamic response of the wall panels. Dynamic finite element analysis conducted on the selected wall panels; based on actual vibration data collected from site during construction activities, strongly indicates that there is a direct correlation between stress pattern of the dynamic analysis and the actual crack pattern observed on the panel. Further analysis confirmed that the vibration has resulted in stress combination outside the experimentally establish failure surface for brick masonry confirming that the current limit is inadequate to safe guard against masonry cracking.