钢筋套筒灌浆接头抗拉性能影响因素试验研究

Analysis of the factors influencing the tensile properties of the reinforced steel sleeve grouting splices

通过对54根钢筋半套筒灌浆接头进行单向拉伸试验,分析灌浆料强度、钢筋锚固长度及钢筋直径对套筒灌浆接头抗拉性能的影响。在此基础上,寻找满足安全使用条件下抗拉性能最弱的接头试件,分析早期振动荷载中振幅和频率变化对接头试件抗拉性能的影响。结果表明:同一钢筋直径灌浆接头试件,抗拉性能随灌浆料强度和钢筋锚固长度的提高而增强;钢筋直径越大,接头抗拉性能越强;早期振动荷载中振幅的增大对试件极限承载力及钢筋与灌浆料之间的锚固性能产生不利影响;频率的变化对试件抗拉性能影响很小;由振动荷载引起的钢筋偏心情况对接头抗拉性能影响微弱。

In order to analyze the influence of the grouting material strength,the anchorage length and the diameter of the reinforced bars on the tensile properties of the sleeve grouting splices,the paper has done an uniaxial tensile tests of 18 groups with a total number of 54 specimens of the reinforced semi-sleeve grouting splices.Based on the aforementioned testing results,we have successfully examined and identified the weakest splice specimens from the tests so as to satisfy the tensile strength demands under the condition of the secure application.Namely,the special grouting splice fixture can be used to simulate the vibration load and change the magnitude and frequency of the vibration strength,the half-sleeve grouting splice specimens,which had just been subjected to the 24 hours’continuous vibration tests and the maintenance tests lasting for 28 days.And,then,the impact of the amplitude and frequency changes due to the first-stage early vibration load on the tensile properties of the splice specimens have been tested and analyzed through the unidirectional tensile test.The testing results demonstrate that the tensile properties of the same diameter grouting splice specimens tend to increase with the increase of the grouting material strength and the anchorage length of the reinforced bars.Moreover,it has been found that,the greater the diameter of the steel bar,the stronger the tensile strength of the splice.That is to say,the increase of the amplitude in the early vibration load tends to have an adverse effect on the ultimate bearing capacity of the specimens and the anchorage performance between the steel bar and the grouting material.Nevertheless.the frequency change of the vibration load has been found little effect on the tensile properties of the specimen.Besides,the eccentricity of the steel bar caused by the vibration load has also little effect on the tensile properties of the splice specimen.According to the unidirectional tension test data of 54 steel bar semi-sleeve grouting splice specimens,the minimum design anchorage length of the grouting splice specimens under their respective service conditions has been given,which can be qualified to provide a basis for saving steel use as much as possible under the safety service conditions for the splice specimens.