Timber gridshell structures get their shape by curving on site initially straight timber laths. This curving process produces stresses in the laths that can easily reach values close to the allowable ones. These initial bending stresses are partially reduced over time due to the rheological behavior of the material. This phenomenon, known as stress relaxation, is beneficial from the structural analysis point of view since it involves a partial recovery of the structural reserve of the laths. Despite the interest of the phenomenon, few researches exist in this regard. This paper presents a review of the test procedures used so far for the measurement of the stress relaxation in timber curved laths as well as the analysis approaches in this respect applied to postformed gridshell structures. It would desirable to carry out experimental campaigns using specimens of structural size and equipment that would make it possible to evaluate the long term bending stress relaxation in timber curved laths with constant radius, so that they were subjected exclusively to pure bending.

Lara-Bocanegra A.J, Majano-Majano A, Guaita M. (2017) Stress relaxation on bending laths: review of test procedures and structural analysis approaches applied to timber gridshells. II Latin American Congress of Timber Structures + II Ibero-Latin American Congress of Timber in Construction (CLEM+CIMAD 2017), Buenos Aires, Argentina.
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