Robot allows verification and design of JOISTS (American prefabricated trusses).
Resistances of joists are defined in the section database created on the basis of the section folder SMI JOIST - FORTY-FIRST EDITION STANDARD SPECIFICATIONS LOAD TABLES AND WEIGHT TABLES FOR STEEL JOISTS AND JOIST GIRDERS.
The option for verification / design of joists is available in Robot only for one of the following American codes: ASD, LRFD or ANSI.
For joists the resistance is specified:
In the Robot steel design / verification module the calculation process of joists proceeds similarly as for standard elements (there are the same dialog for definition of member groups, calculations, configurations). This approach enables the verification of both standard members and joists performed in one calculation session.
Results are presented similarly as for standard members; short results are analogous as for standard steel members; detailed results are presented slightly different; it results from the specific character of a joist.
The verification of a joist is included when evaluating the equivalent load applied to the element (based on the maximal bending moment My) and comparing it with the allowable resistance value read from the database. The verification of displacements is aimed at checking if the equivalent load does not exceed the limit load that causes deflection of the member (1/240*L or 1/360*L).
The design of a family composed of joists consists in finding an element (with the length corresponding to all representatives of the group) whose resistance is the closest to the level of the applied load (but it may not exceed it). The available optimization options allow selection of elements which in the best way satisfy the criteria selected by the user (optimization due to weight and due to section).
Members consisting of joists are only grouped with elements of the same length.