Calculation Model of Shear Capacity of Multiple Composite Core Column Joints Based on Softened Tension-Compression Bar Model

Table 1

The detailed parameters of the frame node in test.

Project			BCJ-1	BCJ-2	BCJ-3
Mandrel	Rectangular frame column	Section (mm × mm)	400 × 400	400 × 400	400 × 400
		Angle steel
		Unilateral longitudinal bars
		Stirrup
	Outer mandrel XZ-1	Section (mm × mm)
		Longitudinal bars
		Stirrup
	Inner mandrel XZ-2	Section (mm × mm)	140 × 140 (circle)	140 × 140 (circle)	140 × 140 (circle)
		Longitudinal bars
		Stirrup
	Strength of concrete (MPa)		C45	C45	C45
	Axial pressure (kN)		1560	2750	1560
	Lower column height		2.4	2.4	3.2
	Height of reverse bending point of lower column		1.2	1.2	1.6
	Height of upper column		1.9	1.9	1.9
	Height of upper column reverse bending point		1.0	1.0	1.0
	Experimental axial compression ratio		0.26	0.45	0.26
	Shear span ratio		1.67	1.67	2.22
Beam	Section (mm × mm)		150 × 380	150 × 380	150 × 380
	Concrete strength (MPa)		C45	C45	C45
	Stirrup
	Beam length (m)		3.75	3.75	3.75
	Length of reverse bending point (m)		1.87	1.87	1.87
	Midspan compression bars
	Negative bending regions
	Lower longitudinal bars
	Longitudinal bars