Abstract：For joints, the deformation mechanism and failure modes are essential to assess their
seismic performance. However, an effective and quantitative evaluation method is still lacking.
The quantitative evaluation method of the deformation mechanism and failure modes of composite
joints are investigated on the basis of the previously proposed multi-scale numerical models. The
deformation-component-proportion (DCP) diagram, which can be calculated directly from the
displacement results of the multi-scale model, is introduced to analyze the deformation mechanism
of the composite joints. The proportions of the beam flexure, column flexure and joint core shear
deformations in the total deformation corresponding to different story drift angles and different
story drift direction angles can be illustrated by the DCP diagram so that the failure mode of the
composite joint can be clearly revealed in any possible story drift direction. The story drift
direction angle can significantly influence the deformation mechanism and failure modes of the
spatial composite joints. Using the DCP diagram, the failure mode should be checked in any
possible story drift direction, and then the design can be optimized to make the composite joints
achieve the expected failure modes in any possible earthquake incident direction.
