Steel Beam Camber from Dead-Load Deflection
Camber = a fraction (75-80%) of the dead-load deflection 5 w L^4 / (384 E I), rounded down to the 1/4 in (AISC).
Example
You enter
- Uniform dead load (kip/ft) 1
- Simple span (ft) 40
- Moment of inertia I (in⁴) 2100
- Modulus E (ksi) 29000
- Camber fraction of DL deflection 0.8
You get
- Dead-load deflection 0.95 in
- Specified camber 0.75 in
Checked against published worked examples from: AISC.
Details, formula, and sources
Scope1.0 kip/ft, 40 ft, I 2100 -> 0.95 in deflection, 3/4 in camber; a stiff 20 ft beam deflecting 0.05 in is left flat (below the ~3/4 in practical minimum). The structural drawings govern.
Formula or tabledelta = 5 w L^4 / (384 E I); camber = fraction x delta rounded DOWN to the 1/4 in (AISC Design Examples v15.1 I.1).
Source and editionSteel beam camber from the dead-load deflection, standard AISC / fabrication practice, by name.
Free accessThe simple-span deflection and the fractional-camber rounding are standard published structural results.
What governsEstimate. AHJ and licensed professional govern.
API field namesw_kip_ft, span_ft, moi_in4, e_ksi, fraction, defl_in, camber_in
- Deflection delta = 5 w L^4 / (384 E I) simple spanbeam theory
- Camber fraction (75-80%) of delta, rounded DOWN to the 1/4 in; none specified below about 3/4 inAISC Design Examples v15.1, Example I.1 and Part III
- Practical minimum not cambered below about 3/4 infabrication practice