Analysis of dynamic behavior of light-frame wood walls under blast loads
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摘要: 为研究轻型木框架墙的抗爆性能,讨论了爆炸荷载作用下轻型木框架墙的数值建模方法,重点探讨了木立柱-面板钉连接动力放大系数以及木立柱破坏准则;基于部分组合理论,通过引入木立柱和轻型木框架墙的动力放大系数实测结果,给出了钉连接动力放大系数的合理取值;构建了考虑木基结构板正交各向异性、钉连接动力非线性力学行为以及木立柱动力弹塑性特征的轻型木框架墙抗爆分析有限元模型。结果表明,提出的模型能够准确预测爆炸荷载作用下轻型木框架墙的动力响应以及木立柱发生断裂的时间和对应的峰值位移。考虑了不同木立柱的材性差异后,模型预测的木立柱断裂后木框架墙动力响应与破坏模式与试验结果一致。本研究提出的模型可为今后轻型木框架结构的抗爆易损性评估提供模型基础。Abstract: Compared to concrete and steel structures, research on the blast resistance of timber structures is relatively scarce. Although experimental studies on the blast performance of light-frame wood walls have been conducted, relevant numerical studies remain limited. This study addresses the numerical modeling of light-frame wood walls under blast loads, with a focus on the determination of the dynamic increase factor (DIF) for nail connections and the failure criteria for wood studs. Based on the partial composite action theory, an analytical expression was derived to describe the relationship between the DIF for nail connections and other mechanical properties of light-frame wood walls, including the stiffness of studs, the stiffness of sheathing panels, and the stiffness of nail connections. A reasonable value for the DIF of nail connections was provided by introducing experimentally measured DIFs for wood studs and wood-frame walls. On this basis, a finite element (FE) model for blast resistance analysis of light-frame wood walls was developed. In this model, the wood studs, sheathing panels, and nail connections were represented using beam elements, shell elements, and discrete beam elements, respectively. The orthotropic characteristics of wood-based structural panels, the nonlinear dynamic behavior of nail connections, and the dynamic elastic-plastic features of wood studs were also appropriately modeled. Verification of the developed model against experimental data indicates that it can accurately predict the dynamic response of light-frame wood walls under blast loads, as well as the time and corresponding peak displacement when wood studs fracture. FE analyses also show that if the variation of the studs’ material properties is reasonably accounted for, the predictions of the dynamic response and failure mode after the fracture of studs are in good agreement with the experimental results. The developed model paves the way for assessing the blast vulnerability of light-frame wood structures in future research.
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Key words:
- blast loads /
- timber structures /
- light-frame wood walls /
- FE modelling /
- nail connections /
- dynamic increasing factors
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试件名称 面板 Pmax/kPa I/(kPa·ms) tp/ms dmax/mm tmax/ms 应变率/s−1 Z/(m·kg−1/3) 墙6-2 11 mm
OSB38.3 403.0 22.0 47 8.9 0.54 9.1 墙7-1 38.2 384.9 20.1 59 9.4 0.55 9.1 墙8-1 9.8 25.1 5.1 8 6.2 1.54 25.0 墙8-2 52.6 163.0 6.2 45 7.9 5.31 7.1 墙9-1 6.6 76.1 23.1 8 10.6 33.0 墙16-1 18.5 mm
胶合板11.5 128.1 22.3 11 9.8 0.12 20.0 墙17-1 12.6 245.7 39.0 13 9.9 0.15 20.0 墙17-2 40.1 813.12 40.5 51 9.9 0.36 8.9 墙19-1 11.0 122.2 22.2 11 9.8 0.12 22.5 墙19-2 42.1 450.4 21.4 56 10.3 0.46 8.5 墙20-1 12.5 160.3 25.6 16 12.1 0.15 20.0 表 2 木框架墙各组件的材料性能实测值[8]
Table 2. Experimental results for the material parameters of the components in the light-frame wood walls[8]
组件 密度/(kg·m−3) MOE/MPa fm/MPa 平均值 COV 平均值 COV 平均值 COV 木立柱 498.0 0.09 9690 0.11 44.5 0.23 OSB 685.0 5550 0.24 28.4 0.31 胶合板 470.9 7120 0.16 41.0 0.28 表 3 激波管试验中木框架墙的弹性响应模拟结果与实测结果的对比
Table 3. Comparison of the experimental and numerical results for the elastic response of the light-frame wood walls in the shock tube tests
试件名称 试验值[8] 模型一 模型二 模型三 模型四 dmax,test/
mmtmax,test/
msdmax,FE/
dmax,testtmax,FE/
tmax,testdmax,FE/
dmax,testtmax,FE/
tmax,testdmax,FE/
dmax,testtmax,FE/
tmax,testdmax,FE/
dmax,testtmax,FE/
tmax,test墙8-1 8 6.2 0.89 1.15 0.84 1.12 0.81 1.10 0.63 1.02 墙9-1 8 10.6 1.35 1.04 1.22 1.00 1.15 0.99 0.82 0.89 墙16-1 11 9.8 1.37 1.02 1.25 0.97 1.10 0.95 0.72 0.74 墙17-1 13 9.9 1.20 1.01 1.09 0.96 0.96 0.94 0.63 0.71 墙19-1 11 9.8 1.35 1.23 1.22 1.19 1.08 1.14 0.70 0.93 墙20-1 16 12.1 1.14 0.97 1.03 0.92 0.93 0.89 0.58 0.72 平均值 1.22 1.07 1.11 1.03 1.00 1.00 0.68 0.84 COV 0.15 0.09 0.14 0.10 0.13 0.10 0.13 0.16 表 4 激波管试验中发生木立柱断裂的木框架墙模拟结果
Table 4. Numerical results for the light-frame wood walls with the studs failing in the shock tube tests
试件名称 试验值[8] 屈服应变×1 屈服应变×2 屈服应变×2.5 dmax,test/mm tmax,test/ms dmax,FE/dmax,test tmax,FE/tmax,test dmax,FE/dmax,test tmax,FE/tmax,test dmax,FE/dmax,test tmax,FE/tmax,test 墙6-2 47 8.9 0.74 0.74 1.02 0.94 1.10 1.02 墙7-1 59 9.4 0.58 0.72 0.81 0.90 0.87 0.97 墙17-2 51 9.9 0.69 0.71 0.89 1.03 0.93 1.03 墙19-2 56 10.3 0.63 0.68 0.84 0.93 0.86 1.09 平均值 0.66 0.71 0.89 0.95 0.94 1.03 COV 0.10 0.03 0.11 0.06 0.12 0.05 -
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