Optimization

Optimize:

Optimization is valid only for steel and wood members. This option allows the engineer to change the existing sections with sections that are recommended (based on explicit criteria) from a collection of sections. In other words, the original section can be replaced with another that resists the imposed loads considering (or not) maximum deflection within given limits and that is located above the original section in the list of sections specified for the optimization.

In the optimization of wood members, the user has to check that the assigned material is adequate for all sections of the collection and the type of loads of the members.

Haunch Optimization (Except for Truss Design Module):

The correct procedure to optimize members with haunches is to assign the same Description (e.g. BEAM1, RAFTER3, GIRDER, etc.) to the beam or rafter segment that has no haunch and to the beam or rafter segment that does have a haunch welded to it. This guarantees that the optimization process will return the same section for the beams/rafters and then possibly a different one for the haunch. The optimization process covers two stages:

The beam/rafter segment with no haunch attached (e.g. BEAM1) is optimized and the most efficient section determined. This process will use the entire database of sections or a collection (sub-group) assigned by the user.
After the optimum section has been defined, the second stage optimizes only the haunches, combining them with the section selected by RE in the first stage, to determine which combination of rafter and haunch results in the most efficient section overall.

If the Description is not the same in the beginning (i.e. the beam+rafter portion is called BEAM1 and the rafter portion BEAM2), the haunched member optimization could return a different section than the one for the single member.

Check (Change only members that fail):

It is similar to optimization, but sections are only changed if they fail to resist the applied loads (i.e. they fail a member code check), therefore sections are replaced only when they are undersized.

Members to optimize or verify:

These are the members to be optimized. The user must choose the description of all the groups of members that will be optimized. It is important to group members (by description) based on how you would like to optimize them. This option has two small tools that allow the engineer to select All the groups shown, or all the groups from members that are currently Selected.

Stress ratio limit:

This is the maximum interaction value or strength ratio that is allowed for member code check. Typically this parameter is equal to or less than 1.0.

Deflection:

A deflection check may be included in the optimization. In this case the program will verify that the members’ deflections are within the given maximum limits for the desired load conditions (usually service conditions). The maximum deflection is specified in absolute value (i.e. 1.0 in) or in function of the member’s length (L/xx, default value: L/360).

Collections for Optimization:

This small worksheet allows the user to choose an optimization set of sections for each group (description). The available tools are:

Assign the selected collection to the group (description).
Assign the selected collection to all the groups (descriptions) in the worksheet.

Section collections:

This window displays all the available collections. Below the window is a button that allows the user to create or edit collections:

Haunch section collections(Except for Truss Design Module):

This window displays all the available haunch collections, the only possible sections are I and T shaped. At the bottom of the window there is a button that allows the creation or edition of collections:

Notes:

When the differences between the former sections to the new sections is big and if there is a big influence of the self-weight in the member forces as in trusses, it is probable that the optimization process will require several iterations to find a good result.
All members in the same group (description) must have the same section assigned.
When the sections are changed, the analysis and design results are lost.
When optimizing (not code checking), if the initial section (that is assigned to the member for the analysis) is not in the selected optimization collection, it will be replaced with the first section in the collection that meets the member code check requirements. This is true whether or not the original section met the member code check requirements.
If there is no assigned optimization collection, a default collection will be selected which has all the sections of the specified shape. In this case the members will be placed in a priority order based on the section area (mass). For example, if the original section is a W 10x12, the new optimized section will be one of the W shapes.
If an optimization collection has been assigned, the priority order is denoted by the order of the sections in the collection. Note that in this case a collection with different types of sections (i.e., W, L, C, etc) can exist; furthermore, a collection with different codes (AISC and AISI) can also exist.
Only steel or wood sections are considered.
The optimization procedure checks strength first (stresses) and then deflections. If the section has to be replaced the program will tell which criteria was not satisfied.
If the following message is obtained: “No suitable section was found. Error in description X”, all sections were checked and none were found to work.