solved example for strength of doubly reinforced concrete beam

Very nice solved example for calculating the nominal moment strength of a doubly reinforced concrete beam is available at http://civilengineer.webinfolist.com/design/prob92.htm

Reinforced Concrete - Singly Reinforced beam

New solved example for Strength of Singly Reinforced concrete beam posted at http://civilengineer.webinfolist.com/design/prob91.htm

New Quiz on Reinforced Concrete

Two New Quiz on Reinforced Concrete design are now posted at
http://civilengineer.webinfolist.com/cequiz/strudes.htm

Revised version of reinforced concrete calculator

Revised version of Reinforced concrete calculator is now posted at
http://civilengineer.webinfolist.com/design/beamanalysis.htm   (FPS/North American Units)
http://civilengineer.webinfolist.com/design/beamanalysism.htm  (SI/Metric Units)

With this calculator now you can calculate the Tensile, compressive and bending moment strengths of rectangular reinforced concrete beam. It will also calculate the strain in the layers of tension and compression rebar which helps in deciding whether steel has yielded or not.

Reinforced concrete

Get updated web resources in reinforced concrete at
http://civilengineer.webinfolist.com/design/rcc.htm

Precautions during hot-weather concreting

Precautions for hot-weather concreting should be planned when the temperature is expected to reach 30 to 35°C or more. These precautions may have one or more of the following applications:

• cooling of concrete ingredients
• dampening of formwork, reinforcement and subbase
• erection of wind breaks and sunshades to protect exposed concrete surfaces
• cooling of containers, pipelines, chutes, etc during transportation of concrete
• completion of transporting, placing and finishing of concrete as quickly as possible
• use of set-retarding admixtures to control premature stiffening of the fresh mix
• use of some chemicals on the exposed surface of concrete to limit evaporation
• immediatly start curing after final finishing is complete
• moist curing to control concrete temperature
• restricting the placement of concrete during night time when the temperatures are generally lower.

Effects of high temperature on concrete

Concrete is essentially a mixture of cement, aggregate and water. Its qualities are greatly affected by temperature during mixing, placing and compacting.

High temperatures can have the following effects on concrete:

• reduced setting times and early stiffening
• increase in the rates of hardening
• loss of 28 day strength
• increase in tendency for plastic shrinkage
• difficulties in the operations of placing and finishing
• development of cold joints - a cold joint is formed when plastic concrete is placed against concrete that has set and started hardening.

Admixtures are added to control these effects of hot temperature.