High standard JGJ3-2002 article 5.2.3: in the vertical load, the frame can be considered when the end of the plastic deformation of the internal force redistribution, the negative moment of the beam multiplied by the amplitude modulation coefficient. The amplitude of the negative moment of the whole frame beam is 0.7 ~ 0.8, and the amplitude modulation coefficient of the negative moment of the frame beam at the end of the beam is expected to be from 0.8 to 0.9...
The specific meaning of moment modulation:(1) the pursuit of conformity with reality(2) reduce the negative moment of Liang Duan, can reduce the negative moment reinforcement at the support, improve the condition of reinforced steel bar in the node area, which is convenient for concrete pouring, and ensure the strength of the node area.Principle: according to a certain proportion to reduce the bending moment of the beam; and then according to the balance conditions of the increase in the midspan moment.Moment amplitude modulation coefficient: 0.8~0.9 for cast-in-place frame; 0.7~0.8 for assembly frame;
The steel frame of the civil high-rise building and the large span hall, etc., and the rod can be a solid or a frame type. The high-rise buildings in foreign countries adopt the steel frame, the construction period is longer and the member section and the weight are bigger. The Empire State Building in New York and Sears Building in Chicago.
The negative moment amplitude modulation coefficient of the steel frame beam should be set 0.7~0.8;A structure consisting of steel beams and steel columns that is capable of bearing vertical and horizontal loads. For industrial and civil buildings with large span or high load.
