This paper reviews an existing classical three dimensional（3D）nonsmooth multi-yield surface plasticity concrete model proposed by Hofstetter and Simon

i.e.the Cap model

details its algorithm and calculation flowchart and implements it into OpenSees

ageneral nonlinear finite element analysis software.The model uses a closest point projection method to compute the stress in each region defined by the yield surfaces

and computes the consistent tangent modulus.As an illustration application example

the paper analyzes the nonlinear dynamic responses of a two-dimensional concrete gravity dam by using this newly implemented Cap model

and verifies the stablity and applicability of the model.The implementation of cap model extends OpenSees′capability to modelling 3Dconcrete structures

so that it can be used to analyze the large-scale hydraulic engineering

e.g.

nonlinear dynamic analysis of concrete gravity dam.