| UHPC双向板抗冲切性能试验 |
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| 引用本文： | 方志,陈佳醒,曹清.UHPC双向板抗冲切性能试验[J].中国公路学报,2021,34(8):91-105. |
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| 作者姓名： | 方志 陈佳醒 曹清 |
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| 作者单位： | 1. 湖南大学 土木工程学院, 湖南 长沙 410000;2. 湖南大学 风工程与桥梁工程湖南省重点实验室, 湖南 长沙 410000;3. 广东省交通规划设计研究院集团股份有限公司, 广东 广州 510000 |
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| 基金项目： | 国家自然科学基金项目（51938012） |
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| 摘 要： | 为明确超高性能混凝土（Ultra-high Performance Concrete，UHPC）双向板在局部荷载作用下的抗冲切性能，以UHPC强度、板厚、配筋率、局部加载面积和加载位置为试验参数，对9块四边简支UHPC双向板进行抗冲切破坏试验，分析UHPC双向板的冲切破坏机理和各试验参数对板抗冲切性能的影响规律。结果表明：试件均发生钢筋屈服后的冲切破坏，板底出现环形裂缝且板内形成冲切锥体；冲跨比小于7时，冲切破坏面倾角和名义抗冲切强度均随冲跨比增加而减小，而冲跨比大于7时，则其基本不变；UHPC强度等级从120 MPa提高到150 MPa时，板的抗冲切承载能力提高5.5%；当板厚由60 mm增加至80 mm和100 mm时，板的抗冲切承载能力分别提高69.7%和1.883倍；相较于1.31%配筋率的试件，2.57%配筋率的试件的抗冲切承载能力提高14.9%；与方形加载板边长为70 mm的试件相比，边长为90 mm试件的抗冲切承载能力提高9.8%；与中部加载试件相比，边部和角部加载试件的抗冲切承载能力分别提高15.3%和13.1%。为避免UHPC双向板发生钢筋网格内的冲切失效，板底受拉钢筋间距不应大于加载板边长与1.15倍有效板厚的和。基于试验结果和相关文献，评估了现有抗冲切承载力计算公式的适用性，并引入冲跨比考虑局部荷载偏置的影响，提出了适用范围更宽的UHPC板抗冲切承载能力计算公式。
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| 关 键 词： | 桥梁工程 UHPC双向板 抗冲切性能 冲切试验 抗冲切承载能力 冲跨比 |
| 收稿时间： | 2020-12-03 |
Experimental Study on Punching Shear Behavior of UHPC Two-way Slabs |
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| FANG Zhi,CHEN Jia-xing,CAO Qing.Experimental Study on Punching Shear Behavior of UHPC Two-way Slabs[J].China Journal of Highway and Transport,2021,34(8):91-105. |
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| Authors: | FANG Zhi CHEN Jia-xing CAO Qing |
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| Affiliation: | 1. College of Civil Engineering, Hunan University, Changsha 410000, Hunan, China;2. Key Laboratory for Wind and Bridge Engineering of Hunan Province, Hunan University, Changsha 410000, Hunan, China;3. Guangdong Province Communications Planning & Design Institute Group Co. Ltd., Guangzhou 510000, Guangdong, China |
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| Abstract: | To investigate the punching shear behavior of ultra-high performance concrete (UHPC) two-way slabs under a local load, punching tests of nine UHPC two-way slabs simply supported on four sides were conducted. UHPC strength, slab thickness, reinforcement ratio, local loading area, and loading position were used as the test parameters. The failure mechanism of UHPC two-way slabs and the effect of the test parameters on the punching shear behavior were analyzed. The results show that all specimens exhibit punching shear failure after the yielding of the longitudinal steel bars on the bottom of the UHPC slabs. A circular crack on the bottom of the specimen and a punching shear cone are observed. The punching failure angle and normal punching shear strength decrease with an increase in the punching-span ratio when the punching shear-span ratio is less than 7, while remaining largely the same when the punching shear-span ratio is more than 7. Compared with the specimen with a UHPC of 120 MPa, the punching shear capacity of the specimen with a UHPC of 150 MPa increases by 5.5%. When the slab thickness increases from 60 mm to 80 mm and 100 mm, the punching shear capacity of the UHPC slabs increases by 69.7% and 188.3%, respectively. Compared with the specimen with a reinforcement ratio of 1.31%, the punching shear capacity of the specimen with a reinforcement ratio of 2.57% increases by 14.9%. Compared with the specimen with a 70 mm square loading plate, the punching shear capacity of the specimen with a 90 mm square loading plate increases by 9.8%. The punching shear capacity of specimens with a loading position at the edge and corner increases by 15.3% and 13.1%, respectively, compared with the loading position at the mid-span. To avoid punching shear failure within a steel grid, the bar spacing at the bottom of the slab should not exceed the sum of the side length of the loading plate and 1.15 times the effective slab thickness. Based on the results from this study and other studies, the feasibility of some existing equations for calculating punching shear capacity is evaluated. An equation for predicting the punching shear capacity of a UHPC two-way slab is proposed, in which the punching shear-span ratio is introduced to consider the effect of the eccentric load. |
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| Keywords: | bridge engineering UHPC two-way slab punching shear performance punching test punching shear capacity punching shear-span ratio |
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