Experimental Study on the Mechanical Properties of Steel Concrete Column Footings in the Track Supporting Layer of the"Bridge-Station Combined Structure"Hub Station
The frame column of Xiong'an Hub Station supporting the bearing rail layer adopts section steel concrete column.Due to the need of seismic fortification requirements,the section of the steel concrete column is huge.In order to reduce excessive buried footing depth resulted from the traditional embedded steel and concrete column base design and the construction risk hereafter,a new type of semi-buried column base scheme is proposed with the footing steel embedded in the bearing platform about 1.35 times the height of the section of steel,the footing moment reliably transferred to the foundation by using the cross-shaped arrangement of the boot beams,anchor bolts,U-shaped reinforcement,prestressing tendons combination of the structural method so as to reduce the thickness of the foundation bearing platform.In order to verify the reliability of the design scheme,the column base scheme is simplified,and a column base joint model with a scaled-down ratio of 1∶6 is designed and fabricated,and a static test is carried out to obtain the mechanical response and damage of the column base joint under complex loading.Test results exhibite that only cracks appear in the tensile zone of the column base and the steel members of both specimens do not yield under one times of design load,and cracks appear in the compression zone of the column base and bearing platform of both specimens under two times of design load,but the reinforcement bars,the steel boot girders and the steel bones do not yield,which proves that the column base joint has sufficient safety reserve.In addition,the application of prestressing increases the ultimate bearing capacity of the column base joint by 32.9%,and improves the deformation capacity of the column base joint,in which the maximum vertical displacement of the beam end is increased by 92.1%,and the maximum horizontal displacement of the column end is increased by 98.0%;moreover,the application of prestressing could improve the punching shear capacity,and reduce the strain level and the width of the crack at the junction of the bearing platform and the lower level.The structural test results have been applied to the design of Xiong'an Hub Station,and the proposed column base construction form has high safety reserve and good implementability,which can be popularized and applied in the design of similar projects to provide solutions for similar engineering problems.
railway stationbridge-station combined structurecolumn basesteel reinforced concretecomposite structurestatic test
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