GALIĆ, JOSIP1; VUKIĆ, HRVOJE2; KALAFATIĆ, IVAN3

1) Assistant Professor, Ph.D., M.Eng.C.E., University of Zagreb, Faculty of Architecture, Croatia, josip.galic@arhitekt.hr

2) M.Eng.C.E., Radionica statike Ltd., Croatia, hrvoje.vukic@statika.hr

3) Senior Research Assistant, Ph.D., M.Eng.C.E., University of Zagreb, Faculty of Civil Engineering, Croatia, kala@grad.hr

The paper describes experimental research of masonry columns’ behaviour under the load of vertical compression. A total of thirty-four specimens were tested: three unconfined specimens and thirty-one specimens confined with GFRP straps. In addition to the load-bearing efficiency analysis of confined columns in relation to the number of the confinement layers, the intention of these tests was to determine the efficiency of spiral confinement in relation to the conventional confinement. Also studied was the impact of the existing compressive stress in a column during confinement to the final increased load-bearing capacity of the confined column. The test results have shown that all of the confined specimens have a greater load-bearing capacity and ductility than the unconfined specimens. The results of spiral confinement were almost identical to the results of conventional confinement, which is vital considering that spiral confinement is easier to perform. The results of the test lead to the conclusion that the presence of compressive stress in a column during confinement does not significantly reduce the efficiency of confinement. This enables the possibility of effectively increasing the bearing capacity of masonry columns without the need to previously unload the structure, while the structure is in service. The paper also gives expressions for the estimated increase of the compressive strength of confined columns that correspond well with the testing results.

Keywords: Tests, masonry columns, strengthening, glass fibre reinforced polymer straps, GFRP, results