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一、前言在钢筋混凝土(简称R C)设计领域中,尽管理论分析及数学模型日臻完善,计算工具快速准确,以及测试手段日趋精密,但对R C梁的认识,仍不十分了然,特别是当梁身截面在剪力S与弯矩M(乃至轴向力N与扭矩T)的共同作用下,它的受力情况以及斜截面(剪切)的破坏机理,仍有待进一步探讨.自50年代以后近30年来,国内外许多专家学者,对这一专题都进行了大量的实验与理论研究,都期望能从微观现象所得,导向宏观共识,能较统一合理地解决这个难题.但由于机理原因太复杂,迄今仍很难建立起一种与物理意义完全相符的理论计算方法,以致各国的现行设计规范,仍然只能是偏安全地(或加大系数)求助于经验或半经验公式,即令是如此,事后构件受损事例仍在所难免.鉴于混凝土系非匀质体,工作时可变因素太多,例如:骨料咬合滞裂的随机性,以及裂后的应力重分布状态等等.实践证明,斜裂纹也多不与钢筋正交,其
I. Preface In the field of reinforced concrete (RC) design, although the theoretical analysis and mathematic models are improving, the calculation tools are fast and accurate, and the testing methods are increasingly sophisticated, the understanding of RC beams is still not very clear, especially when Under the joint action of shear force S and bending moment M (even axial force N and torque T), its stress condition and the failure mechanism of oblique section (shear) still need to be further explored. Since the 1950s In the recent 30 years or so, many experts and scholars both at home and abroad have carried out a great deal of experimental and theoretical research on this topic, all of whom hope that the macroeconomic consensus can be derived from the microscopic phenomena and can solve this problem in a more unified and reasonable manner. However, due to the mechanism Too complicated, it is still very difficult to establish a theoretical calculation exactly in accordance with the physical meaning so that the prevailing design norms in various countries can only resort to experiential or semi-empirical formulas in partial safety (or increase the coefficient) In the light of the heterogeneous body of concrete, there are so many variables when working, for example, the randomness of aggregate seams and the stress redistribution after fracture, etc. . Demonstrate practice, multiple oblique crack also not orthogonal to the reinforcement which