Anchorage at end support

As simply supported 50% of As should extend into the support. This <9.2.1.2 (1) & Note, 9.2.1.4(2)>

50% of As should be anchored to resist a force of

' Maximum z = 0.947 at mid span and greater towards support.

where

VEd = the absolute value of the shear force a = d, where the slab is not reinforced for shear z = lever arm of internal forces Fe = 29.4 x d / 0.95* d = 30.9 kN / m Anchorage length, /bd lbd = a/b,rqd — 'b.min where a = conservatively 1.0

/brqd = basic anchorage length required

<red = design stress in the bar at the ultimate limit state

E s.prov

— 30.9 x 1000 / 376 —81.5 MPa fbd — ultimate bond stress

— 2.25 n n fct,d where n — 1.0 for 'good' bond conditions and 0.7 for all other conditions — 1.0 n2 — 1.0 for bar diameter < 32 mm fct,d — design tensile strength

— 1.0 x 2.0 / 1.5 — 1.33 MPa fbd — 2.25 x 1.33 —3.0 MPa lb,rqd — (12 / 4) (81.5 / 1.33) —183 mm lbmin — max(10d, 100 mm) — 120 mm lbd — 183 mm measured from face of support

By inspection, using U-bars, OK.

3.3.13 Laps

Lap H12 @ 300 U-bars with H12 @ 150 straights Tension lap, /0 =

12 3 5 6 /b,rqd /0min where a^ = 1.0 (straight bars) a2 = 1 - 0.15 (cd - f) / //> where cd = min(pitch, side cover or cover)

25 mm bar diameter : 12 mm

3 — 1.0 (no confinement by reinforcement) a5 — 1.0 (no confinement by pressure) «« — 1.5

where

<red = the design stress at ULS at the position from where the anchorage is measured.

Assuming lap starts 500 mm from face of support (587.5 mm from centreline of support): MEd = 29.5 x 0.59 - 12.3 x 0.592 / 2 = 15.2 kNm ^sd = MEd / (Asz)

= 15.2 x 106 / (376 x 144 / 0.95) =267 MPa fbd = ultimate bond stress

771 = 1.0 for 'good' conditions

ct.k

<3.1.6 (2) & NA> <Table 3.1> <Table 2.1N & NA>

= max[0.3 x 1.5 x 229; 15 x 12; 200] = max[124; 180; 200] = 200 mm

= 1.0 x 0.84 x 1.0 x 1.0 x 1.5 x 329 — 200 = 414 mm But good practice suggests minimum lap of max[tension lap; 500] .'. lap with bottom reinforcement = 500 mm starting 500 from face of support.

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