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.