Experimental Research On Fatigue Properties Of Planting Bar Concrete Beams Under Cycle Load

The planting-bar technology is advanced and widely used in fields of building maintenance,reinforcement and reconstruction,etc.The static tests of planting-bar technique made are far more than the fatigue tests.With the wide application of planting bar technology in concrete beams,it is very important to study the creep properties of the planting-bar concrete beams under the fatigue properties.This thesis includes two tests on10 planting-bar concrete beams,the first is static test on 4 embedded concrete beams;the second is fatigue test on the remaining 6 beams.Conclusions are drawn through the comparison,computation and analysis from experimental phenomenon and test data of deflection,reinforcement strain,concrete strain,bearing and creep capacity.The results of static test on planting-bar present that with the increase of planting-bar beam depth,the cracking load of planting-bar changes a little,yet the ultimate bearing capacity rises significantly,when the plant steel depth reaches a certain value to continue to increase the depth of planting bar,ultimate bearing capacity increase is not obvious;during the loading,a weak surface comes up between the new and old concrete interface,meanwhile,inclined cracks appear in the bar ends due to the shear stress.The results of fatigue test on planting-bar indicate that in the fatigue loading and the increase of depth,fatigue loading reduces the negative effect on the girder deformation and stress.Compared with the failure modes between the static and fatigue test on beams,fatigue loading causes failure morphology shifting,fatigue failure test affects shear failure in the bar beam end,fatigue loading makes the planting-bar beam end develop into another weak position;the first 500 thousand fatigue loading do great harm to planting-bar beam fatigue and creep damage;deepening the planting-bar depth in the bar end and adding stirrups are effective to limit creep development,this thesis suggests 25 d is proper planting-bar depth of planting beam;this thesis proposes the definition of fatigue creep and formulas of planting-bar beam fatigue creep under the fatigue loading,providing a reference for the planting-bar beam failure analysis.