Constraint forces are directly proportional to the stiffness of the system, so the size of the constraining force reduction depends on the ability of the system to reduce stiffness by the cracking of concrete, the plasticizing of reinforcement, or a time‐dependent process. Constraint forces can be differentiated in two cases: internal forces due to constraints that have the same or opposite action effects as the load in the relevant cross sections. For the first case, extensive experimental investigations have already been performed, and the results have been presented. For the second case, new extended experimental and numerical investigations were carried out to understand the development of the constraint. In these new tests, the concrete strength, percentage of reinforcement, and slenderness were varied. The obtained results serve to assess how constrained forces can be considered in the design of concrete structures.

中文翻译：

---

施加变形产生的约束力的扩展实验和数值研究

约束力与系统刚度成正比，因此约束力减小的大小取决于系统通过混凝土开裂，钢筋的塑化或随时间变化的过程来降低刚度的能力。约束力可以分为两种情况：由于约束而产生的内力与相关横截面中的载荷具有相同或相反的作用效果。对于第一种情况，已经进行了广泛的实验研究，并给出了结果。对于第二种情况，进行了新的扩展实验和数值研究，以了解约束的发展。在这些新测试中，混凝土强度，增强百分比和细长度均发生了变化。