Prestressed Concrete

Select ALL CORRECT option(s) which can be considered to check whether the flexural stresses in a prestressed concrete beam are within the allowable stresses at the transfer and the service stages.

A post-tensioned concrete member of span 15 m and cross-section of 450 mm x 450 mm is prestressed with three steel tendons, each of cross-sectional area 200 mm². The tendons are tensioned one after another to a stress of...

A post-tensioned concrete member of span 15 m and cross-section of 450 mm $$\times$$ 450 mm is prestressed with three steel tendons, each of cross-sectional area 200 mm 2 . The tendons are tensioned one after another to...

A prismatic cantilever prestressed concrete beam of span length, L = 1.5 m has one straight tendon placed in the cross-section as shown in the following figure (not to scale). The total prestressing force of 50 kN in the...

A simply supported rectangular concrete beam of span $$8$$ $$m$$ has to be prestressed with a force of $$1600$$ $$kN.$$ The tendon is of parabolic profile having zero eccentricity at the supports. The beam has to carry a...

A pre-tensioned rectangular concrete beam $$150$$ $$mm$$ wide and $$300$$ $$mm$$ depth is prestressed with three straight tendones, each having a cross-sectional area of $$50$$ $$m{m^2},$$ to an initial stress of $$1200$...

A rectangular concrete beam $$250$$ $$mm$$ wide and $$600$$ $$mm$$ deep is pre-stressed by means of $$16$$ high tensile wires, each of $$7$$ $$mm$$ diameter, located at $$200$$ $$mm$$ from the bottom face of the beam at...

Which one of the following is categorized as a long-term loss of prestress in a prestressed concrete member?

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...

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 mo...

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 $$20$$ $$mm$$ (belo...

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

As per Indian standard code of practice for prestressed concrete $$(IS:1343-1980)$$ the minimum grades of concrete to be used for post-tensioned and pre-tensioned structural elements are respectively

$$IS:$$ $$1343 – 1980$$ limits the minimum characteristic strength of pre-stressed concrete for post tensioned works and pretension work as

A simply supported prestressed concrete beam is $$6$$ $$m$$ long and $$300$$ $$mm$$ wide. Its gross depth is $$600$$ $$mm.$$ It is prestressed by horizontal cable tendons at a uniform eccentricity of $$100$$ $$mm.$$ The...

A beam with a rectangular cross section of size $$250$$ $$mm$$ wide and $$350$$ $$mm$$ deep is prestressed by a force of $$400$$ $$kN$$ using $$8$$ numbers $$7$$ $$mm$$ $$\phi $$ steel cables located at an eccentricity o...

A prestressed concrete rectangular beam of size $$300\,\,mm \times 900\,\,mm$$ is prestressed with an intial prestressing force of $$700$$ $$kN$$ at an eccentricity of $$350$$ $$mm$$ at midspan. Stress at top due to pres...

A prestressed concrete rectangular beam of size $$300\,\,mm \times 900\,\,mm$$ is prestressed with an intial prestressing force of $$700$$ $$kN$$ at an eccentricity of $$350$$ $$mm$$ at midspan. Stress at top due to pres...

Let $$jd$$ be the lever arm between the resultant tensile force $$T$$ in the reinforcing prestressing steel and the resultant compressive force $$C$$ in concrete of a reinforced / prestressed concrete beam. When subjecte...

The loss of prestress due to elastic shortening of concrete is least in

A uniformly distributed load intensity, $$w$$ acting on a simply supported prestressed concrete beam of span $$L,$$ producing a bending moment $$M,$$ at mid-span is to be balanced by a parabolic tendon with zero eccentri...

A prestressed concrete beam has a cross-section with the following properties: Area $$A = 46,000\,\,m{m^2},$$ $${\rm I} = 75.8 \times {10^7}\,\,m{m^4},$$ $${Y_{bottom}} = 244\,\,mm,$$ $${Y_{top}} = 156\,\,mm.$$ It is sub...

A rectangular simply supported prestressed concrete beam of span $$L$$ is subjected to a prestressing force of $$P$$ acting centrally at end sections and the prestress tendons are parabolically draped with maximum eccent...