Continuum finite element mdeling of concrete structural ：混凝土結構的連續(xù)有限元建模

1、continuum finite element modeling of concrete structural components- nilanjan mitracrack modeling for concretediscrete crack modeladvanced remeshing(ingraffea & saouma, cervenka)adaptive boundary/fem(carter, spievak)advanced fem meshfree fem (belytschko) x fem (sukumar, moes, dolbow) lattice met

2、hods(van mier, bolander)smeared crack modelenriched continuaempirical global(vecchio & collins, hsu)phenomenological(rots, de borst, willam, crisfield, blaauwendraad) fixed crack coaxial rotating multi-directional fixeddamage plasticity(de borst, simo, lubliner, desai, fenves, govindjee)micropla

3、ne models(bazant, prat, ozbolt, caner)cosserat continua(cosserat, green, rivlin,mindlin, vardoulakis,muhlhaus, de borst, willam, sluys, etse)higher order gradient(aifantis, vardoulakis,de borst, pamin, voyiadjis)embedded discontinuity(jirasek, lotfi, shing, spencer, belytschko, sluys,larsson, simo,

4、oliver,armero, olofsson) kos sos skonmodels done with tno dianaconstitutive models for continuum femcompressive model for concrete: yield surface drucker-prager flow rule - associative compression hardening/softening function - calibrated to match popovics relation plastic strain is zero till 30% of

5、 the strength is achieved suitable for biaxial loading - 16% increase in strengthtensile model for concrete: linear tension cut-off hordijk model for tension softeningmodel for reinforcement steel: associated von-mises plasticity with strain hardeningmodel for bond in between reinforcement and concr

6、ete: elastic radial response transverse response is calibrated to match the eligehausen model for bondbenchmark analysis using dianafracture energy tests at uw:00.0050.010.0150.020.0250.030.0350100200300400500600700800displacement (in)load (lbs) exp. data: fr-33-r1exp. data: fr-33-r2exp. data: fr-33

7、-r3exp. data: fr-33-r4simulated datadeflected shapecracksmartin, j., stanton, j., mitra, n., and lowes, l. n.(2007), aci materials journal, 104, 575-584 parametric study for fracture energy testvariation with ftvariation with ec00.0020.0040.0060.0080100200300400500600700800displacement (in.)load (lb

8、s.) experimentalprototype simulated10% increase10% decrease00.0020.0040.0060.0080100200300400500600700800displacement (in.)load (lbs.) experimentalprototype simulated10% increase10% decreaseparametric study for fracture energy test00.0020.0040.0060.0080100200300400500600700800displacement (in.)load

9、(lbs.) experimentalprototype simulated10% increase10% decreasevariation with gf00.0050.010.0150.020.0250.030100200300400500600700800displacement (in.)load (lbs.) experimentalprototype simulated (with 0.001)tssfc model with 0.001tssfc model with 0.05tscrc modelvariation with shear retention,different

10、 crack modelsparametric study for fracture energy test00.0040.0080.0120.01402004006008001000displacement (in.)load (lbs.) experimentalprototype - 8 noded 2*2 integrationprototype - 8 noded 3*3 integrationprototype - 4 noded 2*2 integrationdifferent element types00.0040.0080.0120.01601002003004005006

11、00700800displacement (in.)load (lbs.) experimentalprototype simulated (with 60)prototype simulated (with 90)variation with threshold angle q4 (2*2) q8 (2*2) q8 (3*3) benchmark analysis using dianabeam flexure tests:without bond-slip perfect bondwith bond-slipwithout bond-slip perfect bondbenchmark a

12、nalysis using dianaflexural bending mechanism bond testanchorage mechanism bond testbond tests:compressive stress distribution within the jointjoint regiontop reinforcement bar steel stress four noded quad elements for concrete drucker prager associated plasticity for compression phenomenological mu

13、lti-directional fixed crack model for tension linear tension cut-off & hordijk tension softening curve truss element for reinforcement steel in the connection region von-mises plasticity for reinforcement steel interface elements to model bond radial response : elastic transverse response: nonli

14、near calibrated to eligehausen uniaxial bond model elastic elements with cracked stiffness to model the beams and columnsmodel highlightsjoint analysiscrack developmentstudies carried out with abaqusmodel material propertiescompression stress-strain curve : popovics equation1973.tension behavior : m

15、itra 2008.linear response : 30% of maximum compressive strength.concrete model: concrete damage plasticity.beam-column joint modelbeam and column as line elementconnection regionmonotonic increasing lateral loadconstant axial loadsimulated joint with loading and boundary condition.transfer of force/

16、moment to joint : distributing coupling .beam-column joint model cont.column as line elementreinforcements(24/12 for column and 16/12 for beam)joint regionbeam as line element beam-column joint model cont. studies made up to 2% drift. nature of loading :behavior of the beam-column joint under lateral loading cont.bending stress at 2% driftshear stress concentration at joint facebehavior of the beam-column joi