Behaviour And Rehabilitation Of Queen Post Timber Trusses:A Case Study

Abstract

The availability of a wooden queen post truss of the early nineteenth century has provided a unique opportunity to evaluate performances and need for restoration of these structures, and to assess the possible intervention procedures, resorting to both traditional and innovative (glued in steel bars) methods. The truss has been characterized geometrically and statically, and its material (Abies alba Mill) has been classified. The damages have been identified using non-destructive test methods, and the actual performance of each timber element of the truss has been assessed by means of full scale loading tests in the elastic field. The same type of tests has been carried out on those components that had undergone restoration. The data gathered in the diagnostic phase have provided the input values for numeric simulations aimed to propose a predictive model for the truss. These simulations have been validated against the results of load tests, carried out both under static and cyclic (low-frequency) loads. Results show, on the one hand, the opportunities for intervention on this kind of structures offered by innovative connections exploiting glued in bars, and, on the other hand that the static behaviour of t h~s type of truss requires a rather sophisticated approach to be satisfactorily predicted. 1 Queen post trusses Trusses have long been utilised in timber constructions, becoming the covering support element par excellence. Simple construction, possibility to efficiently exploit a rather abundant and easily processable raw material have made the truss to become the main feature of the decking systems. Transactions on the Built Environment vol 66, © 2003 WIT Press, www.witpress.com, ISSN 1743-3509