Seismic Behaviour of Straight-Tenon Wood Frames with Column Foot Damage

Shengcai Li,Lei Zhang,Zhijun Jiang,Hongzhen Luo

doi:10.1155/2019/1604208

Shengcai Li, Lei Zhang + Show 2 more

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https://doi.org/10.1155/2019/1604208

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Abstract

Timber buildings might incur damages after a long service, because column foot damage affects the structural performance under the continued use. In this paper, six straight-tenon joint wood frame specimens were prepared with varying degrees of two different damage conditions at a scale of 1 : 3.52. To obtain failure mode and hysteresis performance of the specimens, the low-cycle reciprocating loading test was conducted. The stiffness degradation curves and equivalent viscous damping curves of the damaged wood frames were also analysed. The mechanical characteristics of the wood frames with column foot damage under the low-cycle reciprocating load were then simulated using the finite element method, and the results were compared to the test results. It is determined that as the degree of column foot damage increases, the fullness and peak of the hysteresis curves for wood frames, the equivalent viscous damping coefficients, and the overall seismic behaviour of the wood frame all gradually decrease. The skeleton curves obtained by finite element analysis and tests showed good agreement, verifying the influence of column foot damage on the seismic behaviour of ancient wood frame structures.

Highlights

Timber buildings might incur damages after a long service, because column foot damage affects the structural performance under the continued use
With reference to the specifications recorded in Yingzao Fashi (Treatise on Architectural Methods) of the Song Dynasty [18], six wood-framed specimens containing single-storey straight-tenon joints were constructed in two groups at a scale of 1 : 3.52, determined by a ratio of 1 cm to 2 Fen-II. e specimens were handmade by carpenters according to traditional practice, with each specimen as shown in Figure 1. e dimensions of the structural components in the straight-tenon wood frame models are provided in Table 1. ese specimens were made of Los Angeles Douglas fir and were naturally dried for half a year
Under the low-cycle reciprocating lateral loading plan, the six wood-framed models with deterioration at the column foot exhibited similar structural responses: (1) During the initial stage of test loading sequence, a gap was observed between the straight-tenon joint and the mortise that, with the application of lateral displacement, began to gradually compress to produce a squeaking sound. e wood frame was observed to slightly rock

Summary

Introduction

Timber buildings might incur damages after a long service, because column foot damage affects the structural performance under the continued use. Yao and Zhao constructed a friction-slipping seismic isolation model for a column and foundation stone by conducting an in-depth study of the friction-slipping seismic isolation mechanism present in the foundations of wood-framed ancient buildings and provided judging criteria for the slipping of the column foot [14]. He and Wang studied the rotational behaviour of the column foot during the rocking process accounting for the compression effect and proposed a theoretical restoring moment model for the column foot joint [15]. In the present study, a series of straight-tenon wood frames were constructed to investigate the impact of timber column foot damage on the seismic behaviour of the overall frame

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