In vertical load, the ends of the beam were influenced by negative bending moment. The forward lateral load made the left end of the beam to be acted on by positive bending moment and cancelled out with the negative bending moment caused by vertical load; the negative bending moments under vertical load and the forward lateral load were superimposed at the right end of the beam, and the cracks grew to 0.1 mm~0.2 mm in the top.
Under the superimposition of negative bending moments, the cracks ranging from 0.2 mm to 0.4 mm were appeared in the top of the splicing, and prestressed tendons almost yield.
The negative bending moment
peak occurs when the gust excitation has already subsided and it is mainly driven by the free response of the elastic structure, as the wing springs back after having reached the maximum upward bending.
It is concluded that the bending moment of the FIM part decreases as the mold temperature difference increases because the negative bending moment
becomes larger with the increasing deflection against the normal direction of the film surface.
The maximum bending moment above the sliding surface is located at a depth of 2.0-2.5 m from the pile top, and the maximum negative bending moment
below the sliding surface is located at a depth of 4 m from the pile top, which are the weakest parts of the pile.
So, it appears that the combined rigidity of compressed flange and the web, for a steel panel under negative bending moment
, remains the first parameter influencing the load carrying capacity of the cross-section.
Negative Bending Moment
and Small Eccentric Compression
The negative bending moments
produced by the eccentric tendon at the moment of failure were 13.88, 11.89, 19.16, and 14.71 kN-m for specimens F2/OAK-1 to 4, respectively.
One of the criteria for fixing the cable prestressing force is aimed at the reduction of max positive and negative bending moments
(the presented method with some modifications is valid also for other purposes: controlling the permissible tensile and compressive stresses, etc.) (Kachurin, Bragin 1971).