预应力空腹式钢骨混凝土梁受弯性能研究

RESEARCH ON BENDING PERFORMANCE OF PRESTRESSED LATTICE TYPE STEEL REINFORCED CONCRETE BEAM

通过5根无粘结预应力空腹式钢骨混凝土梁和1根非预应力空腹式钢骨混凝土梁的受弯试验,分析梁截面应变分布、变形、预应力筋内力增量发展及裂缝分布规律。结果表明:在其它参数条件相同的情形下,对空腹式钢骨混凝土梁施加预应力,可显著提高梁的抗裂承载力;以受拉区混凝土开裂和受拉钢骨下边缘屈服为转折点,试验梁的荷载-变形曲线呈三直线特征;破坏形态与非预应力空腹式钢骨混凝土梁相比裂缝出现较迟,裂缝向上开展缓慢,主裂缝特征不明显;建立的无粘结预应力空腹式钢骨混凝土梁的抗裂承载力和极限承载力计算公式与试验结果吻合较好。

Five unbonded prestressed lattice type steel-reinforced concrete beams and one lattice type steel-reinforced concrete beam were tested. The sectional strain variation, deformation, tendon stress increment development and crack distribution were analyzed further. The results show that applying prestress to a lattice type steel-reinforced concrete beam can improve crack bearing capacity obviously under the same other parameters. The load-deformation curves take the crack of tensile region concrete and the yield of tensile steel lower flange as deviation points and appear a trilinear characteristic. The beam failure modes are compared with those of a non prestressed lattice type steel-reinforced concrete beam, the crack appears late and develops more slowly, and the main crack characteristic is not obvious. The calculation results obtained by using crack and ultimate beating capacity formulas suggested in this paper are in good agreement with the experiment ones.