Construction Points cold-rolled ribbed steel bars: drawn at random from each batch of steel specimens CRB550 two straight rebar wholesale, a tensile test, a bending test done, the test results shall comply with the tensile strength. Buying time when one of the indicators do not meet the above requirements CRB550 straight rebar, steel bar in the batch should take double the number of samples should be retested review a sample still fail, it is determined that the batch of substandard steel CRB550 straight steel companies should clear the construction site. Cold-rolled ribbed steel Environmental requirements: Steel test temperature is generally in the range of 10 ~ 35 ℃ be, there are strict requirements of the test, the temperature was 23 ± 5 ℃. Determination of tensile strength Rm: Look steel surface quality, reinforcement should be no harmful surface defects. Mark, the application of small marks, fine scribe or ink line mark the original gauge the distance, but not with the cause of premature rupture notch mark. The ratio of the sample to calculate the value of the original gauge length rounded down to the nearest multiple of 5mm, the middle value to a larger one of rounding. The original gauge length shall be marked accurately to ± 1%.