دانلود A modified constitutive model for FRP confined concrete in circular sections and its implementation with OpenSees programming

Abstract

OpenSees is a well-recognized open source platform with high compatibility, and it has a well-developed fiber element method to cope with nonlinear structural analysis. Fiber reinforced polymer (FRP) confined concrete can effectively improve the  seismic  performance  of  concrete  structures.  However,  sophisticated  constitutive  models  for  FRP  confined  concrete  are  not  available  in  the  current  version  of  OpenSees.  In  this  paper,  after  reviewing  several  typical  FRP  confined  concrete  constitutive models,  a  modified  constitutive  model  for  FRP  confined  concrete  in  circular  sections  was  proposed  based  on  Lam  and  Teng (2003)’s  model  with  four  main  modifications  including  the  determination  of  FRP  rupture  strain,  ultimate  condition,  envelope  shape,  and  hysteretic  rules.  To  embed  the  proposed  constitutive  model  into  OpenSees  is  a  practical  solution  for  engineering simulation.  Hence,  the  secondary  development  of  OpenSees  New  User Mat  was briefly demonstrated  and a  set  of  critical  steps were depicted in a flow chart. Finally, with the numerical implementations of a series of FRP confined concrete members covering a  wide  range  of  load  cases,  FRP  confinement  types  and  geometric  properties,  the  utility  and  accuracy  of  the  proposed  model compared with Lam and Teng (2003)’s model and new material secondary development in OpenSees were well validated.