| The RC flat plate construction systems are being widely used because of its advatanges of simple construction,high clearance and low cost,but it also has the risk of progressive collapse in the event of terrorist attacks.Therefore,it is very necessary to carry out research on the prevention of progressive collapse of flat plate construction systems.In this paper,13 slab-column connections are designed and made by changing the concrete strength,the ratio of reinforcement and the ratio of shear span.Among them,10 are tested in two stages of blast loading and static loading,2 are tested in static loading and 1 is pre-tested.The main work of this paper is as follows:(1)The mechanical characteristics of slab-column connections under blast load are analyzed.Combined with the additional load-time curve and strain-time curve of slabcolumn connections under blast load,the test results show that the slab-column connections are under the action of eccentric compression,full section tension and torsion.(2)The influence of concrete strength,reinforcement ratio and shear span ratio on hole area,additional load,punching capacity and ultimate bearing capacity is analyzed.The test results show that the area of the hole produced by the blast load decreases with the increase of concrete strength and increases with the increase of the shear span ratio.The additional load increases with the increase of concrete strength and decreases with the increase of shear span ratio.The punching capacity and ultimate bearing capacity of the slab-column connections improve by the increase of strength of concrete,the ratio of reinforcement and the ratio of shear span.(3)The impact of blast load on the bearing capacity of slab-column connections is analyzed,the failure mechanism of slab-column connections during cable action stage is revealed,and the calculation formula of ultimate bearing capacity of slab-column connections after the blast load is put forward.The test results show that after the blast load caused by 300 g emulsion explosive,the punching capacity of slab-column connections in this test decrease by 46.71% and the ultimate bearing capacity decrease by 13.99% at most. |
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