When calculating the internal force of continuous deep beam by elastic mechanics method, the redistribution of plastic internal force is not considered for the time being. The test shows that there is an obvious redistribution of internal forces in the simply supported deep beam after the oblique cracks appear, and the stress system distribution of the tie-rod arch with longitudinal tensile steel bars as tie bars and concrete on the upper part of the oblique cracks as arch ribs.
Component requirements:
The height and span of deep beams are close, and their mechanical properties are quite different from those of ordinary beams. Under the load, the shear deformation caused by transverse shear force in the beam will cause additional deflection of the beam, so that the deformation of the section perpendicular to the middle plane is no longer perpendicular to the middle plane, but warping, and the normal section strain of the beam does not conform to the assumption of flat section.
In order to avoid the plane instability of deep beams, the code limits the height-width ratio (h/b) or span-width ratio (L0/h) of beams (the section width is not less than 140mm, and when L0/h≥ 1, h/b should not be greater than 25, when L0/h.
It is required that the top simply supported deep beam and the upper and lower continuous deep beams should be connected with other members (such as floors) with greater horizontal stiffness as far as possible. The span-height ratio of capping beam is also clearly stipulated in the Code for Design of Highway Bridges.