分解等截面直梁弯曲变形和剪切变形的试验方法

提出能够准确分解等截面直梁弯曲变形和剪切变形的试验方法. 基于小变形理论，在梁的弯曲变形可以由梁段上缘、下缘附近纵向纤维长度变化表征的假定下，推导采用实测梁段上、下纵向纤维长度变化计算弯曲挠度的方法，获得弯曲变形对上、下纵向纤维端点对角线长度变化的影响. 在梁的剪切变形只引起梁段对角线长度变化的假定条件下，推导利用实测梁段对角线长度变化计算剪切挠度的方法. 在非对称荷载条件下，确定实测截面转角引起挠度的计算方法. 上述弯曲挠度、剪切挠度和截面转角引起的挠度合并构成目标截面基于变形分解的推算挠度. 推算挠度完全独立于目标截面的实测挠度. 完成4个钢筋混凝土等截面梁试件的荷载试验，实测了剪跨长度范围上缘、下缘附近纵向纤维的长度变化、对角线长度变化和截面转角. 在各级荷载下，利用实测数据计算得到的荷载点截面推算挠度与实测荷载点挠度吻合良好，验证了该变形分解方法的可靠性.

Experimental approach for decomposition of deflection of prismatic beams into flexural and shear deformations

An approach which could accurately decompose deflection of prismatic beams into flexural and shear deflections was proposed. Equation for estimation of decomposed flexural deflection was derived, and changes of diagonals in length caused by those experimentally measured longitudinal deformations were developed based on small deformation theory and under the assumption that flexural deflection can be represented by longitudinal deformation of upper fiber and lower fiber along prescribed beam segment. Equation for estimation of decomposed shear deflection was derived in terms of experimentally measured diagonal deformations under the assumption that shear deformation can only change length of diagonals of prescribed beam segment. Formula for estimation of deflection caused by rotation of target section was derived in terms of experimentally measured target section rotation for asymmetrical load condition. The fore mentioned decomposed flexural deflection, decomposed shear deflection and deflection caused by measured target section rotation add up to estimated deflection of target section, which is completely independent of directly measured deflection at target section. Loading tests on four prismatic rectangular reinforced concrete beams were conducted. Longitudinal deformation of upper fiber and lower fiber along shear span, diagonal deformations and rotation of load point section were measured. Estimated deflection of load point section calculated by using those measured data accorded with directly measured deflection at each load level, which verified the reliability of the proposed deformation decomposition approach.