Testing of long-term behaviour of pre-stressed timber-to-timber composite (TTC) floors

The paper presents the outcomes of an experimental investigation on the long-term behaviour of timber-to-timber composite (TTC) floors assembled using a cambering-prestressing (CP) procedure previously proposed by the authors. The short-term effectiveness of such technique has been demonstrated in previous literature where it is shown that by exploiting the capability of the screw connectors to apply a compression force on the joining timber members, it is possible to obtain a camber and a prestressed condition without any use of other external devices or propping. To prove the applicability of the aforementioned CP procedure to real life design-scenarios, the long-term efficacy should be investigated. With such aim, four TTC floor specimens of 5.0 m of span and different connection layouts, were loaded in flexure under controlled environmental conditions for a period up to almost 1.5 years. One of the main results from the long-term monitoring of the specimens is that the floors uplift achieved by applying the CP procedure was found to be persistent over time with minimal camber losses. (C) 2019 Elsevier Ltd. All rights reserved.