Lateral Resistance Performance of Damaged Timber Frames with Two Reinforcement Methods

doi:10.12141/j.issn.1000-565X.240124

Abstract

Abstract:

Fiber-reinforced polymer (FRP) reinforcement and self-tapping screw reinforcement are two commonly used methods for strengthening timber structures. Currently, research on reinforced glued laminated timber (glulam) structures primarily focuses on changes in strength after reinforcement, with relatively limited data on lateral resistance performance. Moreover, studies on reinforcing earthquake-damaged glulam frames are scarce. To investigate the lateral resistance performance of earthquake-damaged glued laminated timber (glulam) frames reinforced using different methods, two earthquake-damaged glulam frames were strengthened separately with carbon fiber-reinforced polymer (CFRP) and self-tapping screws, along with the addition of diagonal braces. The specimens were subjected to horizontal cyclic loading, and the experimental results were compared and analyzed. The test results indicate that both reinforcement methods effectively prevented the longitudinal splitting of the timber. However, compared to the specimen reinforced by self-tapping screw, the specimen reinforced by fiber-reinforced polymer shows significantly higher initial stiffness and peak load-carrying capacity, which can better suppress the development of cracks. The hysteretic curves of both frames exhibit a relatively anti “S” shape, with an obvious pinching effects. On the basis of the tests, simplified models of two frames were established using Open Sees. The models were calibrated based on experimental data. The hysteretic curves obtained from the calibrated models were in good agreement with the experimental results, verifying the accuracy and rationality of the model and laying the foundation for further parameter analysis. Furthermore, the influence of gravity loading for the specimens on the elastic stiffness and the maximum loading capacity was also investigated. It indicates that gravity load has an undeniable impact on the lateral resistance performance of timber frames, providing a scientific parameterized analysis for the seismic damage of reinforced timber frames.

Key words: damaged timber frame, fiber-reinforced polymer reinforcement, self-tapping screw reinforcement, hysteresis curve, parameter analysis

CLC Number:

TU366.3

CAO Jixing, HAN Mengfan, BAO Chao, HE Haijie, LIU Yingyang. Lateral Resistance Performance of Damaged Timber Frames with Two Reinforcement Methods[J]. Journal of South China University of Technology(Natural Science Edition), 2025, 53(2): 107-114.

Figures/Tables 15

Table 1

Fig.1

Fig.2

Fig.3

Fig.4

Fig.5

Fig.6

Table 2

Key mechanical performance parameters of two frames"

试件	$P P$ /kN	$Δ P$ /mm	$P u$ /kN	$Δ u$ /mm	$K e$ /（kN·mm^-1）
比值	1.05	0.97	1.05	1.02	1.08
RF-FRP	121.69	161.67	97.35	169.17	0.64
RF-STS	115.49	167.08	92.39	165.46	0.59

Table 2

Fig.7

Table 3

Table 4

Table 5

Fig.8

Fig.9

Table 6

Elastic stiffness and the maximum load capacity under various gravity loads"

试件	重力荷载/（kN·m^-1）	$P P$ /kN	$K e$ /（kN·m^-1）	$P P$ 的下降幅度/%	$K e$ 的下降幅度/%
RF-FRP	f₁=0	122.75	0.817	0.00	0.00
	f₂=4	118.04	0.786	3.84	3.79
	f₃=8	113.34	0.755	7.67	7.59
	f₄=12	108.63	0.724	11.50	11.38
RF-STS	f₁=0	112.22	0.790	0.00	0.00
	f₂=4	102.00	0.726	9.11	8.10
	f₃=8	92.08	0.661	17.95	16.33
	f₄=12	82.17	0.597	26.78	26.71

Table 6

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构件	截面尺寸	材料名称
梁	280 mm × 180 mm	层板胶合木
柱	280 mm × 230 mm	层板胶合木
隅撑	135 mm × 105 mm	层板胶合木
梁柱、柱基节点连接	6.8级普通螺栓，直径14 mm	45号钢
支撑节点连接	6.8级普通螺栓，直径12 mm	45号钢
钢插板地基节点连接	6.8级普通螺栓，直径30 mm	45号钢
钢插板	厚度10 mm	Q235钢

编号	梁柱接头			编号	柱脚接头
编号	参数	数值		编号	参数	数值
1	e_Pf1	0.90	1		e_Pf1	0.93
2	e_Pf2	1.30	2		e_Pf2	1.68
3	e_Pf3	0.52	3		e_Pf3	0.56
4	e_Pf4	0.35	4		e_Pf4	0.25
5	e_Pd1	1.10	5		e_Pd1	0.99
6	e_Pd2	1.30	6		e_Pd2	1.02
7	e_Pd3	0.42	7		e_Pd3	0.55
8	e_Pd4	1.04	8		e_Pd4	0.92
9	r_DispP	0.70	9		r_DispP	0.70
10	f_FoceP	0.155	10		f_FoceP	0.151
11	u_ForceP	0.101 2	11		u_ForceP	-0.082 0

编号	梁柱接头			编号	柱脚接头
编号	参数	数值		编号	参数	数值
1	e_Pf1	0.012	1		e_Pf1	0.012
2	e_Pf2	0.090	2		e_Pf2	0.080
3	e_Pf3	1.720	3		e_Pf3	1.650
4	e_Pf4	0.190	4		e_Pf4	0.080
5	e_Pd1	0.290	5		e_Pd1	0.280
6	e_Pd2	0.830	6		e_Pd2	0.980
7	e_Pd3	3.370	7		e_Pd3	3.430
8	e_Pd4	3.750	8		e_Pd4	3.680
9	r_DispP	0.70	9		r_DispP	0.50
10	f_FoceP	0.055	10		f_FoceP	0.031
11	u_ForceP	0.003 2	11		u_ForceP	0.032 0

参数	数值		数值
g_K1	1	g_D4	0.8
g_K2	0.5	G_DLim	0.2
g_K3	0.5	g_F1	1
g_K4	0.5	g_F2	0
g_KLim	0.01	g_F3	1
g_D1	0.5	g_F4	1
g_D2	0.5	g_FLim	0.01
g_D3	1	g_E	10

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