Mechanical performance of UHPC keyed epoxy joints under combined bending and shear action
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摘要: 为研究弯剪复合作用下超高性能混凝土(UHPC)键齿胶接缝受力性能,开展了14个UHPC键齿胶接缝剪切试验,主要参数有弯剪比、侧向应力、钢纤维体积掺量(0~2%),研究了在弯剪复合作用下试件的失效模式、界面相对滑移和剪切强度变化规律。研究结果表明:UHPC键齿胶接缝剪切强度整体随着弯剪比的增加而减小,但弯剪比对其剪切强度影响存在明显界限弯剪比,当弯剪比不大于0.4时,弯剪比对接缝剪切强度影响较小;当弯剪比大于0.4时,弯剪比的增加影响较为显著;当UHPC钢纤维体积掺量由0增加至2%时,弯剪接缝试件的剪切强度增长幅度为50.3%;直剪与弯剪接缝试件的剪切强度均随侧向应力的增加而呈线性增长趋势,当弯剪比较大时,侧向应力的增加会显著提升接缝的剪切强度,表明侧向应力与弯剪比对接缝剪切强度存在交互影响。基于试验数据提出的考虑弯矩作用的UHPC键齿胶接缝剪切承载力计算公式,经验证,计算结果与试验数据吻合良好。Abstract: To investigate the mechanical performance of keyed epoxy joints in ultra-high-performance concrete (UHPC) under combined bending and shear action, shear tests on 14 UHPC keyed epoxy joints were conducted with parameters including the bending-shear ratio (a/h), lateral stress, and steel fiber content (0-2%). The failure modes, interface relative sliding, and shear strength variation laws of the specimens under combined bending and shear action were studied. According to the results, the shear strength of UHPC keyed epoxy joints decreases with the higher bending-shear ratio on the whole. However, there is an obvious boundary bending-shear ratio for the influence of the bending-shear ratio on the shear strength. When a/h≤0.4, the influence of the bending-shear ratio on the joint shear strength is small. When a/h>0.4, the influence of the higher bending-shear ratio is relatively significant. When the UHPC steel fiber content increases from 0 to 2%, the shear strength of the combined bending and shear joint specimens rises by 50.3%. The shear strength of both direct shear and bending-shear joint specimens exhibits a linear growth trend with the increase of lateral stress. When the bending-shear ratio is relatively large, the higher lateral stress significantly enhances the shear strength of the joint, indicating an interactive effect between lateral stress and the bending-shear ratio on the joint shear strength. Based on the experimental data, a shear capacity calculation formula for the UHPC keyed epoxy joint was proposed considering the bending moment. Verification results demonstrate a good agreement between the calculated results and the experimental data.
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表 1 试件参数设计
Table 1. Design of specimen parameters
试件编号 弯矩/mm 剪切高度/mm 弯剪比 键齿数量 钢纤维体积掺量/% 侧向预应力/MPa DSK3-F2-S4 0 500 0.0 3 2 4 DSK3-F2-S7 0 500 0.0 3 2 7 DSK3-F2-S10 0 500 0.0 3 2 10 BSK3-0.4-F2-S4 200 500 0.4 3 2 4 BSK3-0.4-F2-S7 200 500 0.4 3 2 7 BSK3-0.4-F2-S10 200 500 0.4 3 2 10 BSK3-0.4-F0-S4 200 500 0.4 3 0 4 BSK3-0.4-F1-S4 200 500 0.4 3 1 4 BSK3-0.2-F2-S4 100 500 0.2 3 2 4 BSK3-0.3-F2-S4 150 500 0.3 3 2 4 BSK3-0.5-F2-S4 250 500 0.5 3 2 4 BSK3-0.5-F2-S7 250 500 0.5 3 2 7 BSK3-0.5-F2-S10 250 500 0.5 3 2 10 BSK3-0.6-F2-S4 300 500 0.6 3 2 4 注:表1中DS为直剪试件;BS为弯剪试件,K后的第1个数字为键齿数量;K后第2个数字为弯剪比a/h;F后数字为钢纤维体积掺量;S后数字为侧向应力。以BSK3-0.4-F2-S4试件为例,其表示该试件类型为弯剪试件,弯剪试件键齿数量为3,弯剪比a/h为0.4,钢纤维体积掺量为2%,侧向应力为4 MPa。 表 2 UHPC的力学性能
Table 2. Mechanical properties of UHPC
钢纤维体积掺量/% 0 1 2 弹性模量/GPa 42.0 44.6 45.7 立方体抗压强度/MPa 124.9 141.6 173.6 单轴拉伸强度/MPa 8.1 11.0 12.1 抗折强度/MPa 30.1 31.7 33.1 表 3 试件主要试验结果
Table 3. Main test results of specimens
试件编号 $ {V}_{\mathrm{c}\mathrm{r}, \mathrm{B}} $/kN $ {V}_{\mathrm{c}\mathrm{r}, \mathrm{S}} $/kN $ {V}_{\mathrm{u}} $/kN $ \frac{{V}_{\mathrm{c}\mathrm{r}}}{{V}_{\mathrm{u}}} $ $ {\tau }_{\mathrm{u}} $/MPa $ {\tau }_{\mathrm{u}}/\sqrt{{f}_{\mathrm{c}\mathrm{u}}} $ DSK3-F2-S4 634 955 0.66 19.10 1.45 DSK3-F2-S7 601 917 0.65 18.35 1.39 DSK3-F2-S10 478 1 009 0.47 20.18 1.53 BSK3-0.4-F2-S4 520 1 253 1 723 0.30 17.23 1.31 BSK3-0.4-F2-S7 725 1 320 1 864 0.39 18.64 1.41 BSK3-0.4-F2-S10 1 178 1 451 2 012 0.59 20.12 1.53 BSK3-0.4-F0-S4 497 830 1 146 0.43 11.46 1.03 BSK3-0.4-F1-S4 901 1 183 1 373 0.66 13.73 1.15 BSK3-0.2-F2-S4 914 1 403 1 780 0.51 17.80 1.35 BSK3-0.3-F2-S4 1 349 1 431 1 663 0.81 16.63 1.26 BSK3-0.5-F2-S4 842 899 1 243 0.68 12.43 0.94 BSK3-0.5-F2-S7 412 782 1 418 0.29 14.18 1.08 BSK3-0.5-F2-S10 590 630 1 835 0.32 18.35 1.39 BSK3-0.6-F2-S4 269 861 1 152 0.23 11.52 0.87 表 4 UHPC键齿胶接缝抗剪承载力计算值与试验值对比
Table 4. Comparison between calculated and experimental values of shear capacity for UHPC keyed epoxy joints
参数 $ {V}_{\mathrm{s}, \mathrm{e}\mathrm{x}\mathrm{p}} $/kN $ {V}_{\mathrm{s}1} $/kN $ {V}_{\mathrm{s}2} $/kN $ {V}_{\mathrm{s}3} $/kN $ {V}_{\mathrm{s}4} $/kN $ \frac{{V}_{\mathrm{s}1}}{{V}_{\mathrm{s}, \mathrm{e}\mathrm{x}\mathrm{p}}} $ $ \frac{{V}_{\mathrm{s}2}}{{V}_{\mathrm{s}, \mathrm{e}\mathrm{x}\mathrm{p}}} $ $ \frac{{V}_{\mathrm{s}3}}{{V}_{\mathrm{s}, \mathrm{e}\mathrm{x}\mathrm{p}}} $ $ \frac{{V}_{\mathrm{s}4}}{{V}_{\mathrm{s}, \mathrm{e}\mathrm{x}\mathrm{p}}} $ 本文试件 DSK3-F2-S4 955 1 029 875 747 1 033 1.08 0.92 0.78 1.08 DSK3-F2-S7 917 1 157 984 872 1 197 1.26 1.07 0.95 1.30 DSK3-F2-S10 1 009 1 281 1 089 996 1 361 1.27 1.08 0.99 1.35 文献[13] K3-F1-D50-S4 772 1 000 850 686 1 005 1.30 1.10 0.89 1.30 K3-F3-D50-S4 984 1 000 850 686 1 005 1.02 0.86 0.70 1.02 K3-F2-D40-S4 881 998 848 711 1 017 1.13 0.96 0.81 1.15 K3-F2-D60-S4 822 1 003 852 662 994 1.22 1.04 0.81 1.21 平均值 1.18 1.00 0.85 1.20 标准差 0.10 0.08 0.09 0.11 表 5 弯矩影响的UHPC键齿胶接缝抗剪承载力计算值与试验值对比
Table 5. Comparison of calculated and experimental shear capacity values for UHPC keyed epoxy joints under bending moment
参数 弯剪比 UHPC抗拉强度/MPa 平接缝剪切面积/$ \mathrm{m}{\mathrm{m}}^{2} $ 阳键齿表面环氧树脂层面积/$ \mathrm{m}{\mathrm{m}}^{2} $ 键齿接缝剪切面积/$ \mathrm{m}{\mathrm{m}}^{2} $ 侧向约束力/MPa 试验承载力$ {V}_{\mathrm{s}, \mathrm{e}\mathrm{x}\mathrm{p}} $/kN 式(6)计算值$ {V}_{\mathrm{s}5} $/kN $ \frac{{V}_{\mathrm{s}5}}{{V}_{\mathrm{s}, \mathrm{e}\mathrm{x}\mathrm{p}}} $ BSK3-0.4-F2-S4 0.4 12.1 20 000 48 540 30 000 4 862 710 0.82 BSK3-0.4-F2-S7 0.4 12.1 20 000 48 540 30 000 7 932 793 0.85 BSK3-0.4-F2-S10 0.4 12.1 20 000 48 540 30 000 10 1 006 873 0.87 BSK3-0.4-F0-S4 0.4 8.1 20 000 48 540 30 000 4 573 552 0.96 BSK3-0.4-F1-S4 0.4 11.0 20 000 48 540 30 000 4 687 672 0.98 BSK3-0.2-F2-S4 0.2 12.1 20 000 48 540 30 000 4 890 789 0.89 BSK3-0.3-F2-S4 0.3 12.1 20 000 48 540 30 000 4 832 753 0.91 BSK3-0.5-F2-S4 0.5 12.1 20 000 48 540 30 000 4 622 674 1.09 BSK3-0.5-F2-S7 0.5 12.1 20 000 48 540 30 000 7 709 751 1.06 BSK3-0.5-F2-S10 0.5 12.1 20 000 48 540 30 000 10 918 778 0.85 BSK3-0.6-F2-S4 0.6 12.1 20 000 48 540 30 000 4 576 639 1.11 平均值 0.94 标准差 0.10 -
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