Some useful tips on reinforced concrete design
While designing the reinforced concrete members, it is necessary to check the steel reinforcement in jobsite prior to arrange concrete. Besides, ensure the concrete foundations, beams, columns, etc. are constructed as per design norms. Often, it is observed that steel beam stirrups employed in reinforced concrete design, are not installed properly.
The beam stirrups are extensively utilized in residential construction. In order to produce perfect architectural design and satisfy building occupant requirements, the sizes of concrete beam are made thinner and their lengths are increased.
In our experience, this has been the result of architectural design and. The higher cost of foundation components like drilled piers is also a major concern. To lessen the requirement of extra piers, the lengths of concrete beam are raised and it leads to the application of steel stirrups.
Concrete beams differ in depth. The shear strength of the beam will be increased by making beam deeper. For insufficient depth, steel stirrups should be included to raise the shear strength of the beam. These stirrups generally belong to one piece of steel that is twisted into a rectangular shape. Often small diameter steel like #3 and #4 rebar is applied. The stirrup normally wraps around the bottom and top bars of the beams.
It is essential to indicate the size, distance and position along the length of the beam where the stirrups will be assigned. Besides, the dimensions of stirrup should also be indicated in the sections in order that the stirrup is manufactured before installation.
Stirrups are suitable for the areas of high shear, like bearing points and under large point loads.
The installer should take proper care for fabrication of the stirrup from one piece of steel and sufficiently overlap each end (speak to the Structural Engineer or refer to the ACI code for variations). Sometimes, the stirrup is not pre-fabricated and the installer attempts to produce the stirrup in the field, once the horizontal bars are already in position. It is normal since the stirrup is built up from two pieces with insufficient lap splice.
The method is simple to set up a stirrup simultaneously the horizontal reinforcement is being installed. To avoid last-minute modifications, it is recommended to consult with the Structural Engineer with any confusion regarding size, shape, spacing and installation of stirrups before inspection.