Seismic performance evaluation of traditional timber Hımış frames: capacity spectrum method based assessment
Bull Earthquake Eng
Seismic performance evaluation of traditional timber Hımıs¸ frames: capacity spectrum method based assessment
Yasemin Didem Aktas¸ 0 1 2 3
Ahmet Tu¨ rer 0 1 2 3
0 Present Address: Epicentre Research Group, Civil, Environmental and Geomatic Engineering, University College London (UCL) , Gower Street, London WC1E 6BT , UK
1 Restoration Program, Middle East Technical University (METU) , Dumlupınar Bulvarı, 06800 C ̧ ankaya, Ankara , Turkey
2 & Yasemin Didem Aktas ̧
3 Civil Engineering Department, Middle East Technical University (METU) , Dumlupınar Bulvarı, 06800 C ̧ ankaya, Ankara , Turkey
Timber constructions have been widely suggested to be seismically resistant based on post-disaster reconnaissance studies. This observation has, however, remained to a large extent anecdotal due to the lack of experimental work supporting it, especially for certain timber architectural forms, including traditional timber frame ''hımıs¸'' structures. To fill this gap, the authors carried out an extensive full-scale testing scheme using frames of various geometrical configurations, tested under reverse-cyclic lateral loading with/ without infill (brick and adobe) or cladding (bag˘ dadi and s¸amdolma) (Aktas et al. in Earthq Spectra 30(4):1711-1732, 2014a, b). The tests concluded that hımıs¸ frames had high energy dissipation capabilities due mostly to nailed connections. Infill/cladding significantly helped improve stiffness and lateral load strength of the frames, and timber type did not seem to make a remarkable impact on the overall behaviour. The current paper, on the other hand, uses test data to calculate capacity/demand ratios based on capacity spectrum method and Eurocode 8 to elaborate more on the performance of ''hımıs¸'' structures under seismic loading. The obtained results are discussed to draw important conclusions with regards to how frame geometry and infill/cladding techniques affect the overall performance.
Timber frame; hımıs¸; Capacity spectrum method
1 Introduction
Traditional hımıs¸ houses are composite structures, characterized by upper floors composed
of a timber frame load-bearing system constructed on top of a masonry ground floor that
may or may not be timber-strengthened. Despite slight differences in different regions,
especially in terms of infill/cladding materials/types, the same form and design principles
were generally applied over a vast geographic area, regardless of differences in climate,
extending from the inner sections of Anatolia to the Balkans and Greece (Kuban 1995;
Cerasi 1998; So¨ zen 2001).
There are many post-disaster studies reporting a favourable seismic performance of
timber frame ‘‘hımıs¸’’ houses (e.g. see Ambraseys et al. 1968 for 1967 Mudurnu
Earthquake; Sahin Gu¨ c¸han 2007; Penzien and Hanson 1970 for 1970 Gediz Earthquake; Erdik
et al. 1992 for 1992 Erzincan Earthquake; Gu¨ lhan and O¨ zy o¨r u¨k Gu¨ ney 2000; Tobriner
2000, and Langenbach 2007 for 1999 Du¨ zce Earthquake; Demirtas¸ et al. 2000 for 2000
Orta Earthquake). In those cases where ‘‘hımıs¸’’ houses were reported to have behaved
poorly, the damage was often either triggered by the failure of masonry ground floor or
initiated by non-structural masonry elements such as chimneys, or associated with lack of
maintenance, material degradation, improper connections, and heavy roofs (e.g. see Erdik
et al. 2002a, b; Koc¸yi g˘it et al. 2002 for 2002 C¸ ay Earthquake and Erdik et al. 2003 for 2003
Bingo¨ l Earthquake).
Despite these post-disaster observations, the seismic resistance of ‘‘hımıs¸’’ houses has
remained largely anecdotal due to the lack of experimental work supporting this
conclusion. To provide this empirical baseline data, in 2010 a research project was set up and
funded by the Scientific and Technological Research Council of Turkey (106M499). To
this end, a number of frame tests and capacity/demand calculations were carried out with
the aim of assessing and quantifying the seismic resistance of traditional timber hımıs¸
frames. The findings from these frame tests have been presented and discussed elsewhere
(Aktas et al. 2014a, b). This paper reports the ATC-40 based capacity calculations using
the data obtained from the frame tests and comparison of these against demand values
Fig. 1 An overall view of the test setup
calculated by using Eurocode 8 (2004), in order to evaluate the seismic performance of
each frame with different geometrical configurations, with and without infill/cladding.
2 Frame tests
For frame tests, a total of 6 frames that reflect the geometrical and constructive features of
traditional hımıs¸ frames were selected from Safranbolu, a UNESCO World Heritage site in
northern Turkey for its authentic townscape characterized by hımıs¸ houses (for more
detailed information about frame selection, see Aktas et al. 2014a). Out of 6 selected frame
geometries, 2 were built twice by local builders using yellow pine and fir (see Aktas et al.
2014a for material properti (...truncated)