Creep factors for timber-timber and Timber-concrete joints

According to Eurocode 5, the additional deformation of joints caused by creep shall be calculated as the short term deformation multiplied by the deformation factor (kdef). The short term deformation shall be determined based on the slip modulus of the joint (Kser). The slip modulus of the joints may be obtained either from the models given in Eurocode 5 for specific types of joints, or alternatively from experimental tests in accordance with EN26891. In experimental tests, the long term deformation is related to the short term deformation through the creep factor of the joints and is determined relative to the initial deformation. In this situation, the deformation factor from Eurocode 5 and the creep factor of the joints have an equivalent meaning. An essential difference is the determination of the short term deformation. In Eurocode 5, it is based on the joint slip modulus Kser, while in the creep tests it is taken as the initial displacement shortly after loading. However, there is no uniform procedure to determine this value and procedures vary widely between laboratories. In the tests considered here, the initial displacement has been determined at 10 minutes after the load application. In this paper, a detailed analysis is made on the determination of creep factors. The results are available from a large number of long term tests on timber-timber and timber-concrete joints. These tests have been performed at Delft University of Technology and at the University of Coimbra. Various types of fasteners have been used and tests have been performed in both climate controlled and uncontrolled conditions, covering the climate classes of service classes 1 and 2 from Eurocode 5. The influence of climatic aspects on the long term deformations is discussed and a proposal for creep factors for different duration of load classes is made.      «

According to Eurocode 5, the additional deformation of joints caused by creep shall be calculated as the short term deformation multiplied by the deformation factor (kdef). The short term deformation shall be determined based on the slip modulus of the joint (Kser). The slip modulus of the joints may be obtained either from the models given in Eurocode 5 for specific types of joints, or alternatively from experimental tests in accordance with EN26891. In experi...     »