Why the longitudinal tie bar adopts screw steel bar, and the transverse transmission bar adopts light round steel bar.
Fine grain hot-rolled steel grades in the hot rolled ribbed bar with English abbreviation "fine" English (Fine) first letter. Such as: HRBF335, HRBF400, HRBF500. There are higher requirements for the seismic structure, the applicable brand is: after the existing brand plus E (such as: HRB400E, HRBF400E).
Steel is known as hot rolled ribbed bar. Ordinary hot rolled steel bars are made up of HRB and the minimum yield point of the brand. H, R, and B are the first letters in English for hot-rolled (Hotrolled), ribbed (Ribbed) and reinforced (Bars) three words. Hot rolled ribbed bar is divided into two levels, HRB335 (old No. 20MnSi), three HRB400 (20MnSiV, 20MnSiNb, old No. 20Mnti), four grade HRB500 three grade.
Longitudinal tie rod. Longitudinal seam usually has longitudinal contraction joint and longitudinal construction joint two kinds, two kinds of longitudinal joints should be provided with tie rod. The bar shall be designed with the length of the threaded steel to ensure the bond between it and the concrete, and the diameter and spacing of the tie rod shall also be guaranteed. Thus, the tie rod can not provide enough tensile force, and when the concrete faceplate is contracted, the longitudinal joint is pulled apart to form a crack.
Dowel arm for transverse construction joint. The transverse construction dowel bar is applied with a light circle and half coated with asphalt, allowing sliding. In practical application, the construction units are convenient for drawing, often use thread steel, and do not apply asphalt. The concrete pouring time on both sides of the construction joint is different, the contraction during the condensation process is not synchronous, and the dowel bar can not be stretched and formed a weak link. Cracks occur at this weak point when concrete slabs contract under loads or natural factors.
