VERIFICATION OF APPROXIMATE ANALYSIS BY BEAM-MODEL FOR THE LOAD-SLIP CHARACTERISTICS OF DRIFT-PINNED JOINTS WITH THE STEEL PLATE INSERTED

Abstract

 Timber structures require many joints connecting the structural columns and beams. Unfortunately it is generally difficult that timber structures have rigid joints. Due to external forces, the rate of deformation at the junction of the deformation of structures increases. Therefore the effect of deformation of joints in wooden structure must be taken into consideration.
 The objective of this study is to verify the approximate analysis for the load-slip characteristics of drift-pinned joints of steel plate inserted by beam-model. The approximate analysis model is composed of divided elements of beam model and supports that have wood spring concentrated on each node while using stiffness matrix of beam modeling general stiffness equation.
 The result of linear analysis with drift-pinned elements whose length is less 0.5 d(d: diameter) was almost same as the solutions of elastic foundation beam theory.
 In order to make the comparison with detailed experimental results, a rigid zone section was set on the base end of an analysis model to restrain the deformation of the thickness of the steel plate. We verified the central loading tests by analyzing a beam model with tri-linear rotation springs and thereby confirmed the validity of the nonlinear model of drift-pin.
 Nonlinear analysis with divided elements of beam model that has tri-linear rotation spring, and wooden embedding spring that has characteristics of 3P-exp function was carried out.
 Accuracy of approximate analysis was examined by utilizing both divided elements and displacement analysis step as parameters. To improve upon accuracy of analyses in the yield hinge region, the number of elements divided at the range of the part of the base end of analysis model is increased.
 Experimental results and analyses with embedded strength formulas using wood specific gravity were compared. The results of this experiment were mostly distributed between the upper and lower limits of analysis results with embedding strength formulas. For analysis model to evaluate the experiment results, it is essential to select the standard embedding strength rather than to be accurate analysis by the number of elements divided
 The strain measurement of drift-pin and nonlinear analysis can show the bending yield point of the moment(My).
 On the allowable stress design of timber structures, the damage limits displacement to the short acceptable shear strength(Pa) of joint in earthquake is significantly affected by the relations between strength(Pa) and strength(Pp) that yield hinge(Mp-strength) occurred.