One of the necessary conditions for using the method of graph multiplication is ( )
A. the bending moment diagram is a straight line under unit load
B. the structure can be divided into straight members with uniform section
C. the flexural rigidity EI of all members is a constant and equal
D. a structure must be a statically determinate structure
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The law of reciprocal displacements is that the displacement caused by the second force in the direction of the first force is equal to the displacement caused by the first force in the direction of the second force.
An actual truss has only axial forces, no bending moments and shear forces.
The rational axial line of a three-hinged arch under downward vertical uniformly distributed load is ( ).
A. Second-degree parabola (二次抛物线)
B. Catenary (悬链线)
C. Hyperbola (双曲线)
D. Cosine curve (余弦曲线)
When establish a virtual work equation, the relationship between force state and displacement state is ( ).
A. Independent of each other
B. The displacement state must be generated by the force state.
C. Mutual causation
D. The force state must be caused by the displacement state.