Portico Farmhouses of the Vistula Delta: Architecture, Current State and Finite Element Modelling of Timber Roof Truss under Material and Cross-section Uncertainty

ABSTRACT

The article focuses on the oldest surviving I-type portico houses located in the Vistula Delta, which were built in the 17th and 18th centuries. The study describes the houses’ origins, structure, details of roof structures and technical condition, and it also includes numerical modelling of a roof truss and its mechanical analysis. Numerical models of the roof trusses are defined and analysed by means of the finite element method. Global sensitivity analysis with the use of the polynomial chaos expansion method is used to study the influence of uncertainties in material properties of wood, such as Young’s modulus and the friction coefficient, and also the beam cross-sectional height in the output of the numerical model of the structure. The outcomes show that the uncertainty of beam height exerts the dominating influence on the maximum deflection of the roof truss, hence accurate measurements of geometry are of great importance in the planning of conservation and renovation of such historic structures.

KEYWORDS:

• Architectural heritage
• carpenters’ marks
• carpentry joints
• global sensitivity analysis
• polynomial chaos expansion
• portico houses
• Sobol’ indices
• timber roof structure
• uncertainty quantification

Acknowledgments

The authors would like to thank the owners of arcaded houses for their consent to perform measurements and photographic documentation.

Conflicts of interest

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work has been partially supported by the National Science Centre (Poland) under [Grant No. 2015/17/B/ST8/03260]. Calculations have been carried out partially at the Academic Computer Centre in Gdańsk.