大跨无粘结预应力高强度纤维混凝土梁受弯性能试验研究及数值分析

Experimental study and numerical analysis of flexural performance of large-span unbonded prestressed HSFRC beam

以高强度纤维混凝土(HSFRC)代替传统的混凝土有望大大提高结构自身的跨度,提高梁的延性及耗能能力。新型材料HSFRC的本构关系是目前的研究热点,但针对大跨足尺的无粘结预应力HSFRC梁受弯试验研究仍不够充分。针对上述问题,以梁长为21m的工形截面大跨足尺无粘结预应力HSFRC梁受弯试验数据为基础,提出了当钢纤维体积掺量为2%时适用于HSFRC梁的材料受拉本构模型,并将其应用于有限元模拟。有限元结果与试验结果比较表明:本文提出的HSFRC受拉本构模型可以反映出HSFRC材料对梁受弯性能的改善作用,且形式简单;使用局部坐标系的Coupling约束可以合理地反映曲线型无粘结预应力筋与混凝土之间的相互作用;本模型及其建模方法适用于大跨无粘结预应力HSFRC梁受弯性能的分析,在一定程度上可以代替试验,能够较准确地反映试验梁受弯变形的规律。

High strength fiber reinforced concrete(HSFRC), which is used to replace the traditional concrete, is expected to greatly increase the structure’s own span and increase the ductility and energy dissipation capacity of the beam. The constitutive relationship of the new material HSFRC is the current research hotspot, but the bending test data of the large-span full-scale unbonded prestressed HSFRC beam is still insufficient. In view of the above problems, based on the bending test data of the large-span full-scale unbonded prestressed HSFRC beam with a beam length of 21 m in an I-section. The tensile constitutive model was suitable for HSFRC beams when the volume content of steel fiber is 2%, which is applied to the finite element simulation. The comparison between the finite element results and the test results shows that the HSFRC tensile constitutive model proposed in this thesis can demonstrate HSFRC materials improvement effect on the bending performance of beams, and the form is simple. Coupling constraint, where local coordinate system is used, can reasonably show the interaction between uncured prestressed tendons and concrete;this model and its modeling method are suitable for the analysis of the bending performance of large-span unbonded prestressed HSFRC beams. It can replace the test to a certain extent, and can more accurately reveal the law of the bending deformation of the test beam.