Experimental study on shear behavior of UHPC-T beams
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摘要: 对9片超高性能混凝土(UHPC)T形梁设计进行了受剪性能试验,分析钢纤维掺量、配箍率和剪跨比等主要参数对试验梁破坏形态、裂缝开展过程和抗剪承载力的响应影响规律。基于公开发表的57片UHPC梁受剪实测数据,分析对比了既有多国规范的抗剪承载力计算方法。试验结果表明:UHPC-T梁具有较高的抗剪承载力和延性,2%~3%的配纤率有助于更好地发挥钢纤维的抗剪贡献,既有规范对UHPC-T梁的抗剪承载力计算偏保守,对钢纤维的贡献有待进一步研究。Abstract: This paper designs nine ultra-high performance concrete (UHPC) T-beams for shear performance tests and analyzes the influence of main parameters, such as steel fiber content, stirrup ratio, and shear span-to-depth ratio on the failure mode, crack propagation process, and ultimate shear strength of the test beams. Based on the published data of the ultimate shear strength of 57 UHPC beams, it compares shear strength calculation methods of existing standards from multiple countries. The results commonly indicated that a higher fiber content increased the ultimate shear strength and ductility. A fiber content ratio of 2% to 3% helps to better utilize the shear contribution of steel fibers. Shear strength equations in existing standards were found to underestimate the shear capacity of UHPC T-beams , and the contribution of steel fibers to the ultimate shear strength of UHPC requires further research.
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表 1 试验梁主要参数
Table 1. Details of test specimens
试件分组 试件编号 钢纤维含量/% 纵向钢筋 纵向配筋率/% 箍筋 配箍率/% 剪跨比 试件数量 F1 1 1
(78.5 kg/m3)Ø20(6) 4.73 - 0 1.59 1 2 Ø20(6) 4.73 Ø12@200(1) 0.71 1.59 1 3 Ø20(6) 4.73 Ø12@100(1) 1.41 1.14 1 F2 1 2
(157 kg/m3)Ø20(6) 4.73 - 0 2.05 1 2 Ø20(6) 4.73 Ø12@200(1) 0.71 2.05 1 3 Ø20(6) 4.73 Ø12@100(1) 1.41 1.14 1 F3 1 3.5
(275 kg/m3)Ø20(6) 4.73 - 0 1.59 1 2 Ø20(6) 4.73 Ø12@200(1) 0.71 1.59 1 3 Ø20(6) 4.73 Ø12@100(1) 1.41 1.14 1 表 2 UHPC配合比
Table 2. UHPC mixture constituents and proportions
成分 F1 F2 F3 UC160干粉/(kg·m–3) 2232 2232 2232 水/(kg·m–3) 192.4 192.4 192.4 高效减水剂/(kg·m–3) 15.38 15.38 15.38 钢纤维/(kg·m–3) 78.5 157 274.8 配纤率/% 1 2 3.5 表 3 UHPC力学性能
Table 3. UHPC mechanical properties
试件编号 Lf /mm df /mm ρf /% fcu /MPa fc /MPa Es /GPa ft /MPa ν F-0 - - - 150.3 90.9 56.3 F1 13 0.2 1 185.6 101.6 59.7 8.8 0.2 F2 13 0.2 2 188 110.3 65.8 10.47 0.2 F3 13 0.2 3.5 191.9 144.3 77.8 14.7 0.2 表 4 实验结果
Table 4. Test results
梁号 λ ρv/% ρf /% Vcr/kN Vexp/kN ∆exp/mm β/ ° 破坏形态 F1-S700 1.59 0 1.0 250 946 15.5 25 剪压 F1-S700-W200 1.59 0.71 1.0 237 938.1 40.54 31 斜压 F1-S500-W100 1.14 1.41 1.0 238.5 1174.9 21.58 40 斜压 F2-S900 2.05 0 2.0 250 773 12.6 36 剪压 F2-S900-W200 2.05 0.71 2.0 250 1020 80.93 34 弯剪 F2-S500-W100 1.14 1.41 2.0 332 1212.6 12.97 45 斜压 F3-S700 1.59 0 3.5 400 1061.8 56.29 33 弯剪 F3-S700-W200 1.59 0.71 3.5 300 1381.1 70.55 44 弯剪 F3-S500-W100 1.14 1.41 3.5 300 1507 69.2 52 弯剪 表 5 UHPC试件基本信息
模型来源 计算公式 DR AS5100-2014 $ {V_u} = {k_v}\sqrt {{f_{cm}}} bz{\text{ }} + \frac{{{A_{sv}}}}{{{s_w}}}{f_{{\text{sy}}{\text{.f }}}}z\cot \theta + 0.7{k_\theta }bd{f_{tu}} $ KCI-2012 $ \begin{gathered} {V_{\text{u}}} = {\emptyset _b}0.18\sqrt {f_c^\prime } {b_w}d + {\emptyset _b}\left( {{f_{vd}}/\tan {\beta _u}} \right){b_w}z + \\ \qquad \;\,{\emptyset _b}\left[ {{A_v}{f_{yv}}\left( {\sin {\alpha _s} + \cos {\alpha _s}} \right)/{s_v}} \right]d \\ \end{gathered} $ AFGC-2002 $ \begin{gathered} {V_u} = \left( {0.21/{\gamma _{cf}}{\gamma _E}} \right)k\sqrt {f_c^\prime } {b_w}d + \left( {{A_{fv}}{\sigma _{Rd,f}}/\tan \theta } \right) + \\ \qquad \;\;\;\left( {{A_v}/{s_v}} \right)z{f_{yv}}\cot \theta \\ \end{gathered} $ -
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