IS 800 truss design
TrussLab checks every truss member to IS 800:2007 (limit state method) for each strength combination, with Indian sections (ISMB, ISMC, ISA, double angles, SHS, RHS and CHS) and a step-by-step calculation report per member.
Limit states checked to IS 800:2007
Every truss member is checked for each strength load combination. The governing combination and limit state are reported per member as a demand-capacity ratio (DCR), and members are colored by DCR in the model view.
| Limit state | IS 800:2007 clauses |
|---|---|
| Tension | 6.2, 6.3.1 |
| Compression | 7.1.2, 7.5.1.2 (single angles) |
| Bending | 8.2.1, 8.2.2, Annex E |
| Shear | 8.4 |
| Combined forces | 9.3.1.3, 9.3.2.2 |
Partial safety factors γm0 = 1.10 and γm1 = 1.25. Compression uses the buckling classes of Table 10, and single angles in compression take the smaller of flexural buckling about the minor principal axis and the equivalent slenderness of 7.5.1.2.
Sections and steels
Indian catalogue (IS 808, IS 4923, IS 1161): ISMB, ISLB, ISJB, ISWB, ISHB, ISSC, ISNPB, ISWPB, ISMC, ISMCP, ISLC, ISJC, ISA, double angle, SHS, RHS and CHS. Steels: E250, E300, E350, E410, YSt240 and YSt310.
Members are grouped (top chord, bottom chord, diagonals, verticals), each group is assigned a catalogue section and one of the standard steels, and individual members can be overridden. Auto-design selects sections that pass the checks; the optimizer also varies geometry and topology.
Calculation report
A step-by-step calculation report is generated for each member, per limit state and governing load combination, with the demand, the design strength and the resulting DCR. The full truss report is exported as PDF.
Verification against published IS 800:2007 examples
Strengths are compared with the IS 800 limit state verification problems of STAAD.Pro (I-sections with and without lateral-torsional buckling, channel, single angle, circular and square hollow sections). The design compressive stresses of Table 9(a) to 9(d) for fy = 250 MPa are reproduced in the test suite for all four buckling classes.
The inputs, reference values, TrussLab values and differences are listed on the verification page, with downloadable project files.
Scope and differences from the code examples
- Bending strength is limited to 1.2 Ze fy / γm0, the limit of Clause 8.2.1.2 for simply supported members.
- Single-angle compression uses the Table 12 constants for two or more bolts and a hinged end.
- Rupture at the end connection (α = 0.8, net area, block shear) is not modelled.
- Analysis is linear elastic and static. Connections are not designed.
Frequently asked questions
Are angle and double-angle roof trusses supported?
Yes. ISA single angles and double angles are in the Indian catalogue and are checked in tension, compression (including 7.5.1.2 for single angles), bending, shear and combined forces.
Is the working stress method supported?
No. IS 800:2007 checks use the limit state method.
Can the design code be changed after the model is built?
Yes. The design code is a project setting. Selecting another code re-runs the member checks and sets that code's default load combinations; the geometry and loads are kept. Any code can be used with any section catalogue.
Are connections designed?
No. TrussLab designs members only. A selected joint with its connected members and forces is exported to IDEA StatiCa Connection for connection design.