Analýza únosnosti vybraných spojů dřevěných konstrukcí kolíkového typu při statickém i cyklickém namáhání

Abstract

Nowadays, the use of timber as a building material is gaining more prominence. When designing timber structures, it is necessary to pay increased attention to the design of their connections. Commonly used connections are dowel-type connections, which are often used in combination with steel plates slotted into cut-outs in timber members. The presented dissertation deals with the behavior of double-shear bolted connections of squared timber and round timber with slotted-in steel plates. Several variants of connections with different distance between the fastener and the loaded end, in the case of squared timber, also with different moisture content were selected for the experimental testing. A total of six types of test specimens were made from spruce timber, for which their selected physical properties were determined and evaluated before the experimental testing. Test specimens of bolted connections were first tested in tension parallel to grain until failure under quasi-static loading. The results of the experiments were used for comparison with calculation procedures according to the standard for the design of timber structures and with calculations according to the theory of linear elastic fracture mechanics. Subsequently, the effect of the end distance on the load carrying capacity of the connections was evaluated. The effect of moisture content on the load-carrying capacity of the connections was expressed using the proposed regression models. The experiments and the analytical models were supported by a simple numerical analysis based on the finite element method. In the second phase of the experimental testing, cyclic, dynamic tests in tension parallel to grain until failure were performed for two selected geometric modifications of squared timber. The results of the cyclic, dynamic tests were used to analyze the stiffness reduction, load carrying capacity and failure mode of the connections. Subsequently, effective reinforcement against brittle failure was applied to several test specimens using structural screws. The main findings of the research were finally summarized in the conclusion.