Structural Performance Evaluation of Beam-Column Joints Using Tension Bolt for CLT Rocking Frames

Abstract

Cross-laminated timber (CLT) mid-to-high-scale buildings are gaining widespread attention recently. However, developing damage control technology for CLT buildings to minimize damage and enable continued use after large earthquakes has not been established. This research aims to realize a wooden building with excellent performance maintenance after an earthquake experience by introducing a passively controlled CLT structure that uses a rocking wall column and a damper as part of the CLT earthquake-resistant frame. In previous research, the full-scale static shear test was conducted on a 1-story 1-bay passively controlled CLT structure by MATSUDA et al. (2023), and the passively controlled CLT structure, which has high performance of energy absorption and high origin return characteristics, were developed. To actively rock the wall columns, the column-beam joints of the passively controlled CLT structure are designed to have low rotational stiffness. In that test, while the behavior of the frame was analyzed, the behavior of the column-beam joint was not comprehensively identified. Therefore, we conducted the full-scale test on the column-beam joint of the passively controlled CLT structure to understand the mechanical behavior of the column-beam joint. Furthermore, the mechanical behavior of the CLT rocking frame proposed in this study was understood. We confirmed the differences in stiffness, maximum moment, force applied to the embedded surface, and size of the embedment and uplift when the joint shape assumed various shapes and positions. We also proposed a method to evaluate the relationship between the bending moment and rotation angle on the column-beam joints. Applying the idea of embedded triangular to the deformation of column-beam joints is a simple evaluation method that uses the compressive force of embedded triangular and the compatibility for the embedded triangular Equations. In this case, it was necessary to evaluate the uplift of the column-beam joints in advance, and we created a spring model to evaluate the uplift. Spring model was characterized by the stiffness of the tensional bolt, washer, and CLT connected in series. Although additional studies are required to reproduce the yield strength, it is believed that the test results can be accurately replicated.