Stiffness Analysis of Connections of LVL Structures with Claw Washers

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UDС

539.4:539.5

DOI:

10.37482/0536-1036-2020-4-157-167

Abstract

The use of claw washers in dowel connections allows to increase the bearing capacity and stiffness of joints. However, joint action of claw washers and dowels in the structures of advanced materials is studied insufficiently. The paper presents the key failures of existing methods for calculating such connections. Differential equations, that simulate the behavior of a dowel connection with claw washers taking into account the possible changes in the shape of claws, wood moisture content and the duration of loading, are presented. Washer dowel and claw are followed the equations for beams secured on a visco-elastic base, using the equation kernel K(τ,t), which reflects the nonlinearity of the factors affecting the deformation of a connection. The dowel deformation equations are given, which are proposed to be solved by the Bubnov-Galerkin method. The obtained expressions are united into a single equation using the Heaviside step functions. The deformation equations are presented as well. They are written taking into account the virtual displacement of a claw in two orthogonal directions. The expressions allow to pass from calculation of washer claws and a dowel to determination the total bearing capacity and joint stiffness. The possibility of plastification due to the changes in boundary conditions is considered for adequate simulation of connection components behavior upon reaching the plastic stage. The article provides a methodology for determining the theoretical displacements and linear stiffness of a connection. The equations are calculated using dependences available from experiments. In the course of solving the equations, it is possible to determine the values of linear stiffness. These values are compared with the experimental data received earlier to assess the adequacy of the obtained solutions. The distribution of theoretical and experimental data have an average convergence of 91 %, which confirms the validity of the presented methodology for determining the stiffness of dowel connections in LVL with claw washers. The proposed methodology can be recommended for more precise calculation of wooden structures in strength and stiffness, which will reduce their material consumption and enhence reliability.

Authors

A.G. Chernykh, Doctor of Engineering, Head of Department
E.V. Danilov, Senior Lecturer; ORCID: https://orcid.org/0000-0002-8919-4600
P.S. Koval, Senior Lecturer

Affiliation

Saint Petersburg State University of Architecture and Civil Engineering, ul. 2-ya Krasnoarmeyskaya, 4, Saint Petersburg, 190005, Russian Federation; e-mail: chagrig@lan.spbgasu.ru, sleepme@mail.ru, pkoval@lan.spbgasu.ru

Keywords

claw washers, LVL, wooden structures, stiffness, connections

For citation

Chernykh A.G., Danilov E.V., Koval P.S. Stiffness Analysis of Connections of LVL Structures with Claw Washers. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 4, pp. 157–167. DOI: 10.37482/0536-1036-2020-4-157-167

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Received on August 30, 2019