When conducting the section analysis on the bearing capacity of the normal section of a doubly reinforced concrete rectangular beam, if [img=46x23]1803b9533db5432.png[/img], the ultimate bending moment the section undertakes can be ( ).
A: calculated by approximating the relationship between [img=8x23]1803b9534526202.png[/img] and [img=14x23]1803b9534d0c9d8.png[/img] as [img=46x23]1803b953549d24e.png[/img]
B: recalculated according to the case that the area of the tensile reinforcements is unknown
C: recalculated according to the case that the area of the compressive reinforcements is unknown
D: determined according to the minimum reinforcement ratio
A: calculated by approximating the relationship between [img=8x23]1803b9534526202.png[/img] and [img=14x23]1803b9534d0c9d8.png[/img] as [img=46x23]1803b953549d24e.png[/img]
B: recalculated according to the case that the area of the tensile reinforcements is unknown
C: recalculated according to the case that the area of the compressive reinforcements is unknown
D: determined according to the minimum reinforcement ratio
举一反三
- In the calculation of the bearing capacity of the normal section of a doubly reinforced concrete rectangular beam, if [img=63x27]1803b9532781df8.png[/img], it indicates that ( ). A: the compressive reinforcements will not yield B: the tensile reinforcements will not yield C: the section is over-sized D: the compressive reinforcements have already yielded when the failure of the beam occurs
- For a given [img=24x27]1803b9532cc8765.png[/img], when calculating the bearing capacity of the normal section of a doubly reinforced concrete rectangular beam, if [img=46x23]1803b95334b0ce7.png[/img], it indicates that ( ). A: the compressive reinforcements are excessively allocated B: the reinforcements in the compression zone are lightly allocated and needs to be reallocated C: The beam section is over-sized D: The concrete strength is too large
- In the calculation of the bearing capacity of the normal section of a doubly reinforced concrete rectangular beam, the reason for the condition [img=63x27]1803b953249aa8d.png[/img] should be satisfied is to ( ). A: ensure the simplification of the calculation diagram B: avoid the occurrence of the over-reinforced failure C: ensure the compressive reinforcements yield at the failure of the beam D: ensure the tensile reinforcements yield at the failure of the beam
- A reinforced concrete rectangular beam of C40 grade concrete is reinforced with HRB400 grade steel bars in tension. Given that [img=14x23]17de816843b92c0.png[/img] is 1.71[img=62x27]17de81684ecebb0.png[/img] and fy is 360[img=62x27]17de81684ecebb0.png[/img] the minimum reinforcement ratio of longitudinal tensile reinforcements should be ( ). A: 0.18% B: 0.19% C: 0.20% D: 0.21%
- If [img=46x23]1803b95368d5b28.png[/img], the concrete fiber strain at the edge of the compression zone at the failure of the beam satisfies the condition [img=59x19]1803b95371d436c.png[/img], and at the same time, the tensile strain of the tensile reinforcements satisfies the condition [img=53x22]1803b95379d4907.png[/img], i.e., the tensile reinforcement has yielded at the failure of the beam, and the failure mode of such beam belongs to the over-reinforced failure.