Margin of bearing capacity of one-way straight mortise-tenon joints based on inspection of apparent damage and rotation angle

In essence, safety evaluation of damaged mortise-tenon joints (MJs) involves checking whether the joints have sufficient residual bearing capacity. However, the load, which is necessary in the calculation process, is difficult to observe in practice, resulting in insufficient reliability of the evaluation results. Thus, this study proposes the concept of a margin of bearing capacity (MBC) of an MJ and presents a calculation method for assessing the safety of one-way straight mortise-tenon joints (OSMJs). In the calculating process, the load was replaced with the observed apparent damage and rotation angle. First, the MBC includes the influence of joint damage and rotation angle on the residual moment bearing capacity of the joint. Second, the apparent damage to an OSMJ is simplified to average section loss rates in the height and width directions, which reduces the amount and dif-ficulty of data acquisition. Third, the damage model of an OSMJ included in the proposed calculation method establishes the transforming relationship between the measured average section loss rate and the damage setting on the model, and avoids the influence of uneven distribution of the actual size reduction on the calculation of the residual moment bearing capacity. The results of unidirectional pushover tests of several damaged and intact OSMJ models showed that most absolute errors between the calculated and measured MBCs were less than 0.04, indicating the accuracy of the proposed method for practical safety assessment of damaged OSMJs.