load combinations for structural steel from different codes

structural steel deflection limits as per various codes

high performance concrete

 high performance concrete

1. In high performance concrete mix design as water cement ratio adopted is low, super plasticizers are
necessary to maintain required workability. As the percentage of mineral admixtures is increased in
the mix, the percentage of super plasticizer should also be increased, for thorough mixing and for
obtaining the desired strength.

2. In M80 and M90 grades of concrete as the water-cement ratios of 0.23 and 0.21 are insufficient to
provide the workability, (the easiness of handling of concrete in all the stages) hence super plasticizer
are necessary for M80 and M90 grades of concrete.

3. In case of combination percentage replacement of mineral admixtures the maximum compressive
strength achieved in M90 grade concrete is 92.4 Mpa with replacement of 33% flyash and 15.13%
Metakaolin

4. In case of combination percentage replacement of mineral admixtures the maximum compressive
strength achieved in M80 grade concrete is 82.2 Mpa with replacement of 20% flyash and 13.23%
of metakaolin.

5. Mineral admixtures such as Flyash, micro silica, metakaolin, also contributes effectively for
achieving high strength.

6. As soon as crack pattern appears, sudden failure is observed in high strength concrete cubes.

7. The scope for using high strength concrete in our constructional activities are more such as precast,
prestressed bridges, multi-storied buildings, bridges and structures on coastal areas. To affect this
change, we will have to revive the designing of structures by encouraging use of high strength
concrete mixes associated with high performance also

stages of canal lining

stages of canal lining

COMPOSITE FLOORS

COMPOSITE FLOORS

Designing a reinforced concrete slab or pre-stressed concrete slab in composite
construction is not different from any conventional R.C. or pre-stressed structures; .  concrete floors using profiled decks are treated in depth. The structural behavior of these floors is similar to a reinforced
concrete slab, with the steel sheeting acting as the tension reinforcement. The main
structural and other benefits of using composite floors with profiled steel decking are:
 Savings in steel weight are typically 30% to 50% over non-composite construction
 Greater stiffness of composite beams results in shallower depths for the same span.

Hence lower storey heights are adequate resulting in savings in cladding costs,
reduction in wind loading and savings in foundation costs.
 Faster rate of construction.

The steel decking performs a number of roles, such as:

•  It supports loads during construction and acts as a working platform
•  It develops adequate composite action with concrete to resist the imposed loading
•  It transfers in-plane loading by diaphragm action to vertical bracing or shear walls
•  It stabilizes the compression flanges of the beams against lateral buckling, until

concrete hardens.

•  It reduces the volume of concrete in tension zone
•  It distributes shrinkage strains, thus preventing serious cracking of concrete.