The bar bends toward the north and west for the bottom bar, and the bar bends toward the south and east for the face bar. And the right angle is the face bar.
Usually the electronic version of the design labeled rebar line with 45 bends at both ends is the bottom of the slab rebar, and 90-degree bends is the negative rebar or face rebar.
The rebar line on the plan without a 45-degree bend at both ends is the bottom of the slab, the other is the negative rebar.
Face bar and bottom bar are mainly used to withstand the load-induced tensile or compressive stress reinforcement, its role is to make the member of the bearing capacity to meet the structural function requirements.
Expanded information:
Selection of plate reinforcement:
(1) The effective width of the plate is a kind of calculation of the folded width, not the actual participation of the plate width, and not the plate participation of the beam bending when the yield width can be achieved.
(2) According to the typical frame designed in accordance with Chinese norms can achieve the maximum angle of interstorey displacement, can take each side of the beam six times the range of plate thickness as the effective width of the plate.
(3) for the frame end nodes, when the straight crossing edge beam bending and torsional stiffness and longitudinal beams compared to the difference is not too much, in the end of the node at the beam on each side of the six times the thickness of the plate as the effective width of the plate can still be taken.
But if the stiffness of the straight edge beam is weak, the effective width of the plate should be reduced accordingly.
(4) While considering the participation of plate reinforcement in beam-end bending, attention should be paid to the anchorage of plate reinforcement and the setting of transverse reinforcement in the perpendicular direction of the plate and beam in order to ensure that the longitudinal plate reinforcement can effectively participate in beam-end bending.
Baidu Encyclopedia-Slab Reinforcement
Baidu Encyclopedia-Stressed Reinforcement