The accurate modeling of connection joints for civil engineering structures is challenging. The conventional approaches generally assume that the joints are either pinned or rigid, while real joints are semi-rigid in practice. Most existing damage detection methods do not consider the semi-rigidity of the joints, and thus may lead to false or inaccurate identification results. Moreover, the joints are more vulnerable to damage compared to other members of the structure. However, only limited studies have focused on the detection of the joint damage, and few have studied the damage in structural members and joints simultaneously for space structures. In this regard, a two-step damage detection method for space frame structures with semi-rigid connections is developed in this study. Rotational springs with some flexibility are used to model the mechanical behavior of the joints, which enables identification of damage in the bar elements as well as in joints. The first step determines the existence and location of the damaged elements using the l₁ regularization technique. In the second step, the damage locations and severities are then identified within the suspicious damaged elements only that are detected in the first step. This process progressively reduces the number of unknown parameters and thus alleviates the instability and divergence problems to improve the damage identification accuracy. An experimental 3D space structure is utilized to demonstrate the effectiveness of the proposed damage detection method. The results show that damage in structural elements and joints can be correctly located and quantified progressively. The numerical investigation shows that the sensitivity of the modal properties with respect to joint damage is much smaller than to damage in bar elements.

土木工程结构连接接头的准确建模具有挑战性。常规方法通常假定接头是固定的或刚性的，而实际接头在实践中是半刚性的。现有的大多数损坏检测方法都没有考虑到关节的半刚性，因此可能导致错误或不正确的识别结果。此外，与该结构的其他构件相比，这些接头更容易受到损坏。但是，只有有限的研究集中在对关节损伤的检测上，很少有人同时研究空间结构的结构构件和关节的损伤。因此，本文研究了半刚性连接空间框架结构的两步损伤检测方法。具有一定灵活性的旋转弹簧用于对接头的机械行为进行建模，从而可以识别钢筋元件以及接头中的损坏。第一步使用以下方法确定损坏元素的存在和位置：l _1种正则化技术。然后，在第二步中，仅在第一步中检测到的可疑损坏元素中识别出损坏的位置和严重程度。该过程逐渐减少了未知参数的数量，从而减轻了不稳定性和发散性问题，从而提高了损伤识别的准确性。实验性3D空间结构被用来证明所提出的损伤检测方法的有效性。结果表明，结构元件和接缝中的损坏可以正确定位并逐步量化。数值研究表明，模态特性对接头损伤的敏感性比对钢筋构件的损伤要小得多。