Should mild steel or high yield steel be adopted as
reinforcement of water-retaining structures?
In designing water-retaining structures, movement joints can be installed in parallel with steel reinforcement. To control the movement
of concrete due to seasonal variation of temperature, hydration temperature drop and shrinkage etc. two principal methods in design
are used: to design closely spaced steel reinforcement to shorten the spacing of cracks, thereby reducing the crack width of cracks; or to
introduce movement joints to allow a portion of movement to occur in the joints.
For the choice of steel reinforcement in water-retaining structures,mild steel and high yield steel can both be adopted as reinforcement.
With the limitation of crack width, the stresses in reinforcement in service condition are normally below that of normal reinforced
concrete structures and hence the use of mild steel reinforcement in water-retaining structure will suffice. Moreover, the use of mild steel
restricts the development of maximum steel stresses so as to reduce tensile strains and cracks in concrete.However, the critical steel ratio of high yield steel is much smaller than that of mild steel because the critical steel ratio is inversely proportional to the yield strength of steel. Therefore, the use of high
yield steel has the potential advantage of using smaller amount of steel reinforcement. On the other hand, though the cost of high yield steel is
slightly higher than that of mild steel, the little cost difference is offset by the better bond performance and higher strength associated with
high yield steel.
reinforcement of water-retaining structures?
In designing water-retaining structures, movement joints can be installed in parallel with steel reinforcement. To control the movement
of concrete due to seasonal variation of temperature, hydration temperature drop and shrinkage etc. two principal methods in design
are used: to design closely spaced steel reinforcement to shorten the spacing of cracks, thereby reducing the crack width of cracks; or to
introduce movement joints to allow a portion of movement to occur in the joints.
For the choice of steel reinforcement in water-retaining structures,mild steel and high yield steel can both be adopted as reinforcement.
With the limitation of crack width, the stresses in reinforcement in service condition are normally below that of normal reinforced
concrete structures and hence the use of mild steel reinforcement in water-retaining structure will suffice. Moreover, the use of mild steel
restricts the development of maximum steel stresses so as to reduce tensile strains and cracks in concrete.However, the critical steel ratio of high yield steel is much smaller than that of mild steel because the critical steel ratio is inversely proportional to the yield strength of steel. Therefore, the use of high
yield steel has the potential advantage of using smaller amount of steel reinforcement. On the other hand, though the cost of high yield steel is
slightly higher than that of mild steel, the little cost difference is offset by the better bond performance and higher strength associated with
high yield steel.
