Slender CRC Columns

CRC is a high-performance steel fibre reinforced concrete with a typical compressive strength of 150 MPa. Design methods for a number of structural elements have been developed since CRC was invented in 1986, but the current project set out to further investigate the range of columns for which current design guides can be used. The columns tested had a slenderness varying from 1.11 to 12.76 and a reinforcement ratio (area of rebar to area of concrete) ranging from 0 to 8.8 %. A total of 77 tests were carried out - 61 columns were tested in ambient conditions and 16 columns were tested in standard fire conditions. The tests showed good correlation between test results and results calculated according to established deisgn guides. The fire tests demonstrate that the load capacity of slender columns can be reduced very quickly due to thermal stresses and a reduction of stiffness - also in cases where temperature at the rebar is still relatively low. However, guidelines for achieving acceptable fire resistance can be determined based on the test results.