1
GATE CE 2009
+2
-0.6
A rectangular concrete beam of width $$120$$ $$mm$$ and depth $$200$$ $$mm$$ is prestressed by pretensioning to a force of $$150$$ $$kN$$ at an eccentricity of $$20$$ $$mm.$$ The cross sectional area of the prestressing steel is $$187.5\,\,m{m^2}.$$ Take modulus of elasticity of steel and concrete as $$2.1 \times {10^5}\,\,MPa$$ and $$3.0 \times {10^4}\,\,MPa$$ respectively. The percentage loss of stress in the prestressing steel due to elastic deformation of concrete is
A
$$8.75$$
B
$$6.125$$
C
$$4.81$$
D
$$2.19$$
2
GATE CE 2008
+2
-0.6
A pre-tensioned concrete member of section $$200\,\,mm \times 250\,\,mm$$ contains tendons of area $$500\,\,m{m^2}$$ at the centre of gravity of the section. The prestress in tendons is $$1000\,\,N/m{m^2}.$$. Assuming modular ratio as $$10,$$ the stress $$\left( {N/m{m^2}} \right)$$ in concrete is
A
$$11$$
B
$$9$$
C
$$7$$
D
$$5$$
3
GATE CE 2007
+2
-0.6
A concrete beam of rectangular cross-section of size $$120$$ $$mm$$ (width) and $$200$$ $$mm$$ (depth) is prestressed by a straight tendon to an effective force of $$150$$ $$kN$$ at an eccentricity of $$20$$ $$mm$$ (below the centroidal axis in the depth direction). The stresses at the top and bottom fibres of the section are
A
$$2.5\,\,N/m{m^2}\,\,\left( {compression} \right),\,\,10\,N/m{m^2}\,\left( {compression} \right)$$
B
$$10\,\,N/m{m^2}\,\,\left( {tension} \right),\,\,2.5\,N/m{m^2}\,\left( {compression} \right)$$
C
$$3.75\,\,N/m{m^2}\,\,\left( {tension} \right),\,\,2.75\,N/m{m^2}\,\left( {compression} \right)$$
D
$$2.75\,\,N/m{m^2}\,\,\left( {compression} \right),\,\,3.75\,N/m{m^2}\,\left( {compression} \right)$$
4
GATE CE 2005
+2
-0.6
A concrete beam of rectangular cross section of $$200\,\,mm \times 400\,\,mm$$ is pre-stressed with a force $$400$$ $$kN$$ at eccentricity $$100$$ $$mm.$$ the maximum compressive stress in the concrete is
A
$$12.5\,\,N/m{m^2}$$
B
$$7.5\,\,N/m{m^2}$$
C
$$5.0\,\,N/m{m^2}$$
D
$$2.5\,\,N/m{m^2}$$
EXAM MAP
Medical
NEET