Wood Beam Depth To Span Ratio

Design a beam depth based on the rule of thumb for estimating the depth of manufactured beams which is to divide the span by 20.

Wood beam depth to span ratio.

Conversely the deflection of a beam can be calculated if the value of the abscissa is known. Wood floor beam joist floor beam vibrating machinery or track support. Often 2x10 joists spaced 24 inches o c. No mention is made of how the depth was chosen but 1 2 per foot of span seems to be the rule used also a rule which i have used for many years as a preliminary choice of beam depth.

Tapered beams deflect as a result of shear deflection in ad dition to bending deflections figs. We have learned from our experience to use at least a 3 1 4 x 131 groove shank nail in a column of four every foot apart down the laminate. Staggered pattern with at least a 3 x 120 nail. E is a ratio that relates the amount a given load causes a material to deform.

Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads. The 2012 irc code calls for a minimum of a 32 o c. Beam depths are typically 5 1 2 inches 7 1 4 inches 9 1 4 inches 11 1 4 inches 11 7 8 inches 14 inches 16 inches 18 inches and 20 inches. It is the ratio of beam span length to its effective depth depth cover.

Beam depth h0 can be calculated for comparison with that given by the design criteria. Wood wood joists. 2 8 2 10 2 12 spaced 12 14 or 16 inches apart maximum slenderness ratio for column l r is 50 steel deflection limit for steel members l 360 for live load only general steel beam depth 1 22 x span depth to span ratio of joists is limited to 1 24 for composite beam to be efficient slab thickness of 4 to 5 1 2 inches. E value or modulus of elasticity of the individual elements.

Beams of more than one ply must be fastened together with either nails or bolts. Of a member is influenced not only by the span but by such variables as spacing. Depth of structural members. It can be used as a quick check for deflection and initial beam size if your beam span depth ratio is exceeding the ratio limited by the design code then you have to incr.

You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. 9 1 and 9 2 and this.