scope:

Clause 1 8.3 applies to doubly symmetrical composite members consisting of three-plate built-up steel H-sections, with plain tie bars welded between the flange tips at regular intervals, in which the cells between the column flanges and the web are completely filled with concrete in the field during construction, provided that

(a) members are axially loaded;

(b) concrete is of normal density and has a compressive strength, f_c, between 20 and 40 MPa;

(c) A_s ≤ A_r 5 0.20 of the gross cross-sectional area;

(d) the full width of flange, b,, is between 0.9 and 1.1 times the section depth, d;

(e) the flanges and the web are of equal thickness, t;

(f) the flange width-to-thickness ratio is not greater than 32;

(g) a pair of continuous fillet welds, sufficient to develop the shear yield capacity of the web, connects the web to each flange;

(h) the vertical spacing of tie bars, s, does not exceed the lesser of 500 mm or two-thirds of the least dimension of the cross-section. The area of a tie bar is the greatest of

(i) 63 mm²;

(ii) 0.01 b_ft ; or

(iii) 0.5 mm² per mm of tie bar spacing;

(i) the tie bars are welded to the flanges to develop the yield strength of the tie bars; the cover of the tie bars is at least 30 mm;

(j) out-of-straightness of the flanges, as measured between any two adjacent ties along the column edges, does not exceed 0.005 times the tie spacing;

(k) the specified yield strength of structural steel, F_y, does not exceed 350 MPa;