Civil engineering board and affiliate programs

 PRE-STRESSED CONCRETE PART 1 Pre-stressing is a way of counteracting the effect of external loads on structure by imposing a state of stresses contrary to the load effects Pre-stressing has two parts Pre-Tensioning Usually straight or harped profiles, mostly used in the precast industry some example would be hollow core slabs, precast beams, Girder beams Post Tensioning Any type of profile, can be precast or cast in place The only basic difference between pre-tensioning and post tensioning is the state of the structural element while the stressing activities are done. In pretension the stressing is applied prior to concreting while in post tensioning the stressing is applied after the concrete is poured and hardened Further, Post Tensioning is divided in to bonded and unbonded systems; we will get in to this in later days. Pre-stressing a concrete element has two effect axial and transversal based on the tendon profile and anchorage selected. We can have...

  A  concrete slab  is a common structural element of modern buildings, consisting of a flat, horizontal  surface made of cast concrete. Steel-reinforcement  slabs, typically between 100 and 500 mm thick, are  most often used to construct floors and ceilings, while thinner  mud slabs  may be used for exterior paving 1.Effective Span for concrete slab design For simply supported slab Minimum of clear span plus effective depth of slab  Center to centre distance between the supports For cantilever slab    Length up to face of support+Half the effective depth.    Where it forms end of a continuous slab, the length of centre of support shall be taken. 2.Limiting Stiffness For span up to 10m, the Basic values of span to depth ration are given below Cantilevers-7 Simply supported- 20 Continuous- 26 3.Minimum Reinforcement for concrete slab design As per clause 26.5.2.1 of IS 456-2000, the minimum reinforcement shall not...