Long-term dynamic stiffness of resilient materials in floating floor systems

Abstract

The number of high-rise residential buildings being constructed in countries with high population density is increasing in response to the need to utilize small areas. In Seoul, which is the densest of the Organization for Economic Co-operation and Development (OECD) countries, high-rise buildings have become more common in response to the considerable population increase. To diminish floor impact sound, resilient materials are generally applied between the concrete slab and the finishing mortar. Floor impact sound is affected by various characteristics of resilient materials such as dynamic stiffness, thickness, etc. Many experimental studies have been conducted to evaluate the impact sound reducing capacity of the materials, and have indicated that the dynamic stiffness of resilient materials has a close relation with the floor impact sound reduction. In most cases, a resilient material having lower dynamic stiffness has better floor impact sound reduction capacity. However, the dynamic stiffness of soft resilient materials could be changed under long-term loading and this could result in an increase of floor impact sound. The variation of the dynamic stiffness of 8 of the most widely used resilient materials under four different loadings were monitored for more than 500days. The test results indicated that the dynamic stiffness of the resilient materials for floor impact sound increased with time, and that the variation of the dynamic stiffness was affected by loading time, weight of loading, and material properties. In addition, the proposed formula predicted the dynamic stiffness of resilient materials subjected to long-term load with reasonable agreement.