The Plastic Behavior of the Section Tests showed that the resistance of the section can be evaluated as the sum of the strength of the three components(concrete,structural steel,reinforcing steel). The maximum stress in concrete is reached when steel is yielded.Since the 04 -steel concrete strain at the maximum stress is about 0.2%, maximum stress is reached simultaneously concrete in the two materials. Ey.s~2%0
The Plastic Behavior of the Section Tests showed that the resistance of the section can be evaluated as the sum of the strength of the three components (concrete, structural steel, reinforcing steel). The maximum stress in concrete is reached when steel is yielded. Since the concrete strain at the maximum stress is about 0.2%, maximum stress is reached simultaneously in the two materials
The plastic resistance to compression of a composite cross section represents the maximum load that can be applied to a short composite column. It is important to recognize that concrete-filled circular hollow sections exhibit enhanced resistance due to the triaxial containment effects.Fully or partially concrete- encased steel sections and concrete-filled rectangular sections do not achieve such enhancement.These two categories are dealt with separately in EC4
The plastic resistance to compression of a composite cross section represents the maximum load that can be applied to a short composite column. It is important to recognize that concrete-filled circular hollow sections exhibit enhanced resistance due to the triaxial containment effects. Fully or partially concreteencased steel sections and concrete-filled rectangular sections do not achieve such enhancement. These two categories are dealt with separately in EC4
Encased Steel Sections and Concrete- Filled Rectangular Hollow Sections The plastic resistance of an encased steel section or a concrete-filled rectangular or square hollow section is given by the sum of the resistances of the components as follows NplRd=Aa fy/Ya+acAc fo/c+A, A,A,and A,=the cross-sectional areas of the structural section,the concrete,and the rein- forcing steel,respectively ffandf=the yield strength of the steel section,the characteristic compressive strength of the concrete,and the yield strength of the reinforcing steel,respectively YY,and Y=the partial safety factors at the ultimate limit state (Y=1.10,Y=1.5,and Y= 1.15) the strength coefficient for concrete,1.0 for concrete-filled hollow sections and 0.85 for fully and partially concrete-encased steel sections. NplRd=Aalyd+Afcd +Asfsd
Encased Steel Sections and ConcreteFilled Rectangular Hollow Sections The plastic resistance of an encased steel section or a concrete-filled rectangular or square hollow section is given by the sum of the resistances of the components as follows
An important design parameter,.δ，the steel contribution ratio,is defined as follows: It is classified as composite if the steel contribution ratio falls within the range of 0.2 <0.9.If is less than 0.2,the column shall be designed as a reinforced concrete column;otherwise,if ois greater than 0.9,the column shall be designed as a bare steel column
An important design parameter, d, the steel contribution ratio, is defined as follows: It is classified as composite if the steel contribution ratio falls within the range of 0.2 ≤ d < 0.9. If d is less than 0.2, the column shall be designed as a reinforced concrete column; otherwise, if d is greater than 0.9, the column shall be designed as a bare steel column
Concrete-Filled Circular Hollow Sections For concrete-filled circular hollow sections,the bearing capacity of the concrete can be increased due to the confinement effect from the surrounding tube. The plastic resistance of the cross section of a concrete-filled circular hollow section is given by: m=An臣+A:n6哈}A生 /is the thickness of the circular hollow section
Concrete-Filled Circular Hollow Sections For concrete-filled circular hollow sections, the bearing capacity of the concrete can be increased due to the confinement effect from the surrounding tube. The plastic resistance of the cross section of a concrete-filled circular hollow section is given by: t is the thickness of the circular hollow section