EMPIRICAL STATIC LOADING TEST ON TRANSFERRING LOAD TO PERPENDICULAR FRAME BY IN-PLANE ECCENTRIC WOODEN WALL

Abstract

 It is important to arrange shear walls well-balanced in a plane, in order to keep balanced stiffness on seismic design of wooden houses. Especially, in case of the house with some high strength shear walls, it sometimes cannot show corresponding shear force to wall magnification, because of joint breaking or planner eccentricity. On Technique of Wall Quantity Evaluation, one of simplified seismic design method, we must check the eccentricity of whole house.
 There are some previous studies about eccentricity behavior of the wooden houses; such as the phenomenon caused under horizontal load on the wooden house arranged the walls unbalanced, and so on. But there is not the study about influence on the perpendicular frame by in-plane eccentric wooden wall under horizontal loading.
 Until the present, the wooden walls have been thought to be able to ignore in-plane torsional moment because of flexible structure. However, recently, developing new high strength materials or construction methods, and being possible to design the plane and the elevation freely, the demand of high strength shear walls is growing gradually. Then it is very meaningful to understand the phenomenon by in-plane eccentric wooden wall.
 Based on the above, this paper reports the results of the verification on the out-of-plane force by in-plane torsional moment, to understand the phenomenon impacted on the perpendicular frame by in-plane eccentric wooden wall, as primary subject, based on static loading test for three structural plywood walls.
 Major findings from the research are as follows:
 (1) First, based on torsional theory by Wagner and St.Venant, as an open cross section member given torsional moment, the estimated formula were led on initial stiffness and out-of-plane force from columns. The condition changing out-of-plane force is clarified by parametric study.
 (2) Second, static loading test was conducted on three structural plywood walls; in-plane eccentricity as parameter. The out-of-plane force of the open cross section wall is larger than one of the closed cross section wall. The value of the walls targeted in this paper has about 6% of the horizontal load.
 (3) Finally, the above formula was found to estimate test result extremely precise. It is found that large out-of-plane force occur to some open cross section walls with large eccentric length, even if wall magnification was low. The rate of out-of-plane force for horizontal load is same extent between the open cross section walls of same size, in spite of horizontal force.