Seismic resistance of fire-damaged reinforced concrete columns

A study was carried out on the assessment of the residual strength and lateral/seismic load capacity of reinforced concrete columns after fire exposure. The mechanical properties of concrete after fire exposure, such as residual tension and compression strength, stiffness and constitutive responses, were reviewed. A nonlinear finite element analysis program, developed for three-dimensional reinforced concrete structures, was employed to estimate the post-fire axial and lateral performance of two full-scale reinforced concrete columns, tested previously at the National Research Council Canada. The results of the axial load-deformation response obtained from the analysis were compared and verified successfully with the test data. The lateral load and deformation responses of the specimens were then estimated using the numericalprogram. The results showed that both the lateral/seismic load capacity and ductility of the two reinforced concrete column specimens decreased noticeably due to the fire exposure. Studies are suggested on fire damage mitigation and post-fire shear strength recovery of reinforced concrete columns.Une \ue9tude a \ue9t\ue9 entreprise qui porte sur l?\ue9valuation de la r\ue9sistance r\ue9siduelle et la capacit\ue9 de charge lat\ue9rale/surcharge sismique des colonnes de b\ue9ton arm\ue9 par suite d?un incendie. On a examin\ue9 les propri\ue9t\ue9s m\ue9caniques r\ue9siduelles du b\ue9ton apr\ue8s l?exposition au feu, telles que la r\ue9sistance \ue0 la rupture en traction et la r\ue9sistance \ue0 la rupture en compression, la rigidit\ue9, ainsi que la r\ue9ponse constitutive. Un programme d?analyse par \ue9l\ue9ments finis du type non lin\ue9aire, mis au point pour les structures en b\ue9ton arm\ue9 tridimensionnelles, a \ue9t\ue9 employ\ue9 aux fins de l?estimation de la performance longitudinale et lat\ue9rale post-incendie de deux (2) colonnes de b\ue9ton arm\ue9 en vraie grandeur, test\ue9es ant\ue9rieurement au Conseil national de recherche du Canada. Les r\ue9sultats de la r\ue9ponse \ue0 la d\ue9formation/en charge longitudinale qui ont \ue9t\ue9 obtenus par cette analyse ont \ue9t\ue9 compar\ue9s et v\ue9rifi\ue9s avec succ\ue8s en regard des donn\ue9es d?essais. On a ensuite estim\ue9 au moyen du programme num\ue9rique les r\ue9ponses des sp\ue9cimens en charge lat\ue9rale et \ue0 la d\ue9formation. Les r\ue9sultats ont r\ue9v\ue9l\ue9 que tant la capacit\ue9 de charge lat\ue9rale/surcharge sismique que la ductilit\ue9 des deux sp\ue9cimens de colonne de b\ue9ton arm\ue9 diminuaient de fa\ue7on appr\ue9ciable par l?exposition au feu. Des sujets d?\ue9tude sont sugg\ue9r\ue9s, qui porteraient sur les mesures d?att\ue9nuation des dommages caus\ue9s par le feu et sur la recouvrance de la r\ue9sistance au cisaillement des colonnes de b\ue9ton arm\ue9 apr\ue8s l?incendie.Peer reviewed: YesNRC publication: Ye