Beam Analysis with Load Cases

How it calculates

The calculator runs a finite element analysis of the beam. It applies AS/NZS 1170.0:2002 load combinations to the loads you enter.

Structural model

You define the total beam length and the position of each support. Support types are fixed, pinned, roller or hinge, and any number of supports is accepted. A support placed away from either end creates a cantilever. The section is entered as bending stiffness EI, axial stiffness EA and self-weight, or linked from a cross-section calculator.

Load input and load case factoring

Loads are entered as characteristic values in distributed, line, and point and moment load tables. Each load is assigned a load type:

• Dead and live: G, Q, and alternative live loads Q2 and Q3
• Wind: ultimate and serviceability, each downward and uplift (Wu, Ws)
• Earthquake: ultimate and serviceability (Eu, Eu2, Es, Es2)
• Snow: ultimate and serviceability (Su, Ss)

The live load factors psi_s, psi_l, psi_c and psi_E come from the Character of Imposed Load you select. Distributed and concentrated live loads take separate factors. By default the calculator runs these combinations:

• Strength: 1.35G; 1.2G + 1.5Q; 1.2G + 1.5 psi_l Q; 1.2G + Wu (down) + psi_c Q; 0.9G + Wu (up); G + Eu + psi_E Q; 1.2G + Su + psi_c Q
• Short-term serviceability: G + Ws (up); G + psi_s Q; G + Ws (down) + psi_l Q; G + Es + psi_l Q; G + Ss + psi_l Q
• Long-term serviceability: G; G + psi_l Q; G + Ss + psi_l Q

You can pick any load case to plot on the shear, moment and deflection diagrams.

Demand outputs

For each demand type the calculator reports the maximum value and which load case governs:

• M+ and M-**: Positive and negative moment demand with the governing load case
• V*: Maximum shear demand with the governing load case
• R*: Bearing demand with the governing load case

A per-span table lists moments for each span, and a per-support table lists the reaction, moment and shear at each support.

Deflection

The calculator reports three deflections. It does not check them against limits, so compare them with your criteria in the member design calculator:

• Short-term (delta_s): maximum deflection from the short-term serviceability combinations, with the governing load case
• Long-term (delta_l): maximum deflection from the long-term serviceability combinations, with the governing load case
• Imposed-load (delta_Q): the deflection from imposed load

Deflections are also listed per span. Second-order effects are not included.

Wind load calculation

Wind pressures come from the AS 4055 wind class you select, from N1 to N6 or C1 to C4. The class sets the ultimate and serviceability free stream pressures, q_u and q_s. You enter the net downward and uplift pressure coefficients, Cpt and Cptup, and the wind load width. Presets for roof members fill in typical coefficients. The default wind load row multiplies each pressure by its coefficient and load width.