Wooden grid wall which is composed by joining half-lap wood in a grid generally has been used as bearing wall. Structural feature of the wooden grid wall is resistance to external force by embedment of half-lap joints at grid intersections, and it is known to have generally excellent deformation performance and high toughness. In addition, wooden grid wall constitutes assembling the half-lap wood in a grid. It was reported that the rigidity and strength vary by the number of half-lap joints. Due to these features, wooden grid wall performance can be altered by changing the number of grids. In this way it can be used as an earthquake resistant element. Because the embedment of wood affects the loading rate, this paper will consider how the structural performance of half-lap joints is affected by the loading rate.
Based on the above background, the purpose of this paper is to accumulate basic data on the dynamic behavior of wooden grid wall. First, dynamic loading tests were done to understand the influence of the loading rate and the number of half-lap joints. In the experiment, as the target specimen had multiple joints, dynamic loading tests were performed to determine hysteresis curve representing the relationship between the bending moment in the joints and the rotation angle. Next, the envelope from the resulting history curve was calculated by considering the number of joints, and it was verified through the summation rule. Finally, the energy absorption performance of half-lap joint was evaluated by calculating the equivalent damping factor and hysteretic energy.
The results of the experiment indicate that in the loading rate range from 0.01 to 50kine, about the strength, the impact of the equivalent damping factor and hysteretic energy on the loading rate could not be confirmed. Regarding rigidity, the large trend with increasing loading rate was confirmed. Through verification using the summation rule, methods to substantially increase rigidity and strength of the test specimen in proportion to the number of joints has been understood. In addition, that this is not affected by grid spacing was also understood. Therefore, the rigidity and strength of the wooden grid walls and the rigidity and strength of the joints constituting the walls could be inferred by multiplying the number of joints. The hysteretic energy become larger with the increase in the number of joints, and the nature of the hysteric energy was not affected by the grid spacing. Irrespective of the loading rate, when the rotation angle was greater than about 0.1 rad, the number of joints, grid spacing and the equivalent damping factor constantstended to converge to a range from 0.10 to 0.15.
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