Expert: Veto Varma - 4/13/2006

Question
-------------------------
Followup To
Question -
what's the "cold  bending test"?
Answer -
Hello Kimo,

Cold bending test is used for testing steel used in building constructions. Steel for concrete reinforcement and prestressed concrete has to be tested in tension and in bending. I assume you are talking about reinforcing steel cold bending test.

Often it is required to bend the reinforcement in concrete and some code stipulates cold bending of the steel. It is of concern to engineers that cold bending should not reduce the strength/life of the steel. Hence cold bending test data is used for this purpose.

Usually it is found that larger the bar dia more susceptible it is to get cracked or break while bending and straightning operation. Usually 90 degree bend is ok.

In the cold bending test the bars speciment is usually bend to 90 degrees or 180 degrees and straighten out. Then these specimens are observed for cracks or breakdown.

If you have further question feel free to contact me.

Regards
Veto

Hello Veto,

I'm very grateful for your answer, but please could you stress more on "cold" (i.e. the difference between the normal & cold bending tests), such as the range of temperature in which the test is performed, how it affects the material,...etc

thanks a lot
Kimo  

Answer
Hello Kimo,

Exact temperature details come in the metallurgical or material science area, but I can provide you with some reference that you can check or have a lead


Investigation in cold bending crack of Phi 40 mm BS460 grade reinforced bar
Dong, A
Shanghai Jinshu (Shanghai Metals) (China). Vol. 22, no. 3, pp. 48-55. May 2000

"Field Bending and Straightening of Reinforcing Steel"
Khossrow Babael, Neil M. Hawkins, Concrete International, January 1992, pages 67-72



Regards
veto