In a two-hinged parabolic arch (consider arch to be initially unloaded...
As loading is UDL and the shape of the arch is parabolic so there will be no moment in the arch rib.
But as the temperature increases in a two hinged arch (degree of indeterminacy one), the horizontal thrust will increase.
Moment due to horizontal thrust is – Py.
So maximum bending moment will be at crown as crown has highest value of y.
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In a two-hinged parabolic arch (consider arch to be initially unloaded...
Introduction:
In a two-hinged parabolic arch, an increase in temperature induces a bending moment in the arch rib. This bending moment is not uniform throughout the arch, but rather it is maximum at the crown of the arch.
Explanation:
When the temperature of the arch increases, the arch rib experiences thermal expansion. This expansion causes the arch rib to elongate, resulting in a change in the shape of the arch. This change in shape induces bending in the arch rib.
No bending moment in the arch rib:
If there were no change in shape due to temperature increase, there would be no bending moment in the arch rib. However, since the arch rib elongates, it experiences bending.
Uniform bending moment in the arch rib:
The bending moment induced in the arch rib is not uniform throughout the arch. This is because the arch rib experiences greater elongation and hence greater bending at the crown compared to the springing points.
The maximum bending moment at the crown:
The maximum bending moment occurs at the crown of the arch. This is because the crown is the highest point of the arch and experiences the greatest elongation due to thermal expansion. As a result, the arch rib bends the most at the crown, leading to the maximum bending moment.
The minimum bending moment at the crown:
The minimum bending moment does not occur at the crown of the arch. Since the arch rib experiences greater elongation at the crown, the bending moment is maximum at this point.
Conclusion:
In a two-hinged parabolic arch, an increase in temperature induces a maximum bending moment at the crown of the arch. This is because the crown experiences the greatest elongation due to thermal expansion, resulting in the maximum bending of the arch rib.
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