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In fixed beam the maximum deflection at __________ is reduced.
Centre
Supports
At point of loading
Throughout
Centre
In a fixed (encastr├й) beam, the rotational restraint provided at the supports significantly reduces the central deflection compared to a simply supported beam ┬╖ This end-fixity generates internal moments that oppose the curvature, thereby increasing the stiffness of the beam structure.
In a fixed (encastr├й) beam, the rotational restraint provided at the supports significantly reduces the central deflection compared to a simply supported beam ┬╖ This end-fixity generates internal moments that oppose the curvature, thereby increasing the stiffness of the beam structure.
╬┤max,fixedтАЛ=192EIPL3тАЛ тАФ Maximum deflection at center for a point load P at center of a fixed beam
╬┤max,simpleтАЛ=48EIPL3тАЛ тАФ Maximum deflection at center for a point load P at center of a simply supported beam
The end-fixity prevents rotation at the supports (╬╕=0), leading to the development of fixing moments ┬╖ These moments act in opposition to the sagging moment caused by external loads, resulting in a net reduction in the bending moment and consequently a reduction in the central deflection by a factor of 4 for a central point load.
Fixed beams are statically indeterminate to the second degree.
The rotational restraint at the supports reduces the maximum deflection by 75% compared to simply supported beams.
Fixing moments at the supports in a fixed beam with a central load are тИТPL/8.
Higher stiffness and lower deflection.
Improved structural stability and load-carrying capacity.
Sensitive to support settlement/subsidence.
Thermal stresses are induced due to restricted expansion.
Continuous slab construction.
Integrated structural frames where beam-column joints are rigid.
The deflection at the supports of a fixed beam is always zero due to the support conditions.
Option B (Supports) is incorrect because supports in a fixed beam have zero displacement by definition, so 'reduced' implies a relative change in a non-zero value, which refers to the span center.
A is correct тАФ The rotational restraint at the supports of a fixed beam reduces the central deflection significantly compared to a simply supported beam.
Always remember that for any point load, the ratio of maximum deflection between a simply supported beam and a fixed beam of the same span is 4:1.