Guidelines for On-Site Assessment of Historic Timber Structures

Abstract

In the scope of COST IE0601-WoodCulther (http://www.woodculther.org) it was agreed to produce Guidelines for the Assessment of Historic Timber Structures, covering the principles and possible approaches for the safety assessment of old timber structures of historical relevance, that could be used as the basis for possible European Standards, as discussed with CEN/TC346 (Conservation of cultural heritage). This was targeted at all those concerned with the conservation of heritage buildings. It should also help decision-making regarding the need for immediate safety measures. Its aim is to guarantee that inspection and assessment measures provide the necessary data for historical analysis, structural safety assessment and planning of intervention works, while having minimal impact on the building fabric (the original materials, structural systems and techniques).This paper provides information on the criteria to be used in the assessment of load bearing timber structures in heritage buildings. It covers the preliminary assessment (desk survey, preliminary visual survey, measured survey, structural analysis and preliminary report), as well as the detailed survey of timbers (with a special emphasis on visual strength grading on site) and carpentry joints. The subsequent diagnostic report and the detailed design of repairs are outside its scope.

Inspection and condition assessment of existing timber structures

“…However, there is currently a lack of harmonized European standards in this field [24]. Systematic review of criteria to be used in the assessment of load-bearing timber structures in heritage buildings is presented by Cruz et al [4]. The main objective of this paper has been to present non-destructive and semi-destructive test methods that are widely used for assessment of old and protected heritage structures, and to illustrate such methods through a case study involving Technical Museum Nikola Tesla in Zagreb, Croatia.…”

Seismic strengthening and seismic improvement of timber structures

“…-Traditional carpentry joints transmit forces between connected elements by contact and friction; yet, contact pressure may be reduced in seismic or other exceptional conditions; 16 contact may be decreased or even eliminated also by unexpected out-of-plane forces; metal connectors must be applied to prevent disassembly, yet they should not alter the working modality in normal conditions; in particular, the connection stiffness should not be significantly increased; the strengthening interventions should not induce parasitic effects like over-stiffening; in particular the relative rotational capacity between connected members should not be drastically reduced or eliminated;…”

“…In particular, Guidelines for interventions on wooden artefacts have been issued by UNI, the Italian Organization for Standardization as UNI 11138 [15], while a document developed as a result of a COST action, [16] offers guidance for the assessment of such structures. These documents are not specifically prepared in relation to seismic situations, but may be considered a basis for developing heritage compatible interventions in the line of seismic improvement as defined above.…”

Research on structural stability of the traditional timber houses in Bursa-Turkey

“…As suggested in guidelines for the assessment of historic timber structures (Cruz et al 2015), a desk survey was carried out prior to the visits to gather all the necessary information on the buildings, then a preliminary visual and measured survey was done. A tape meter, a laser meter and a digital camera were used.…”