Web Opening Check

A web opening can be added to a composite member using member data. The member will be checked according to AISC Design Guide 2: Steel and Composite Beams with Web Openings. The web opening size and any required reinforcement will not be designed.

Web Opening Limitations

A web opening check can only be performed on a member when LRFD load combinations are used. Design Guide 2 accommodates ASD, but requires a load factor of 1.7 for both dead and live loads. Therefore, a load class which consists of ASD load combinations will not be checked for web openings.

Adding a Web Opening

A web opening can be added to a composite member or members using Web Opening Data. To assign a web opening to a member, first select Web Opening Data within the Composite service, edit the web opening properties, save and close properties menu, and close the web opening data window. If members were selected before selecting Web Opening Data, they will receive the data; otherwise, the command line will prompt for members to be selected.

Options for Web Opening

Within the member data dialogue to define a web opening, several options are presented.

• A checkbox which must be checked in order to specify that a web opening exists on the member.

• An option for the shape of the opening. The choices for the shape are either rectangle or circle. The default option is rectangle.

o If the shape is set to rectangle, the Position and Size of Opening dialogue below will accept the parameters of the rectangular opening. The height and length of the opening, as well as the position of the opening (Distance from start of member to opening) must be specified. Additionally, an eccentricity may be specified. A positive eccentricity value denotes an opening above the mid-point of the member and a negative eccentricity value denotes an opening below the mid-point of the member.

o If the shape is set to circle, the Position and Size of Opening dialogue below will accept the parameters of the circular opening. The diameter of the opening, as well as the position of the opening (Distance from start of member to opening) must be specified. Additionally, an eccentricity may be specified. A positive eccentricity value denotes an opening above the mid-point of the member and a negative eccentricity value denotes an opening below the mid-point of the member.

• A checkbox specifying whether or not the opening is reinforced.

o If the opening is reinforced, the Reinforcement dialogue box will appear below the shape parameters to accept the reinforcement parameters. The options and inputs for the reinforcement are 1) to include Reinforcement on both sides of the web 2) the Width of the reinforcement 3) the Thickness of reinforcement 4) Depth from outside edge of flange to centroid of reinforcement (from the top flange) and 5) Depth from outside edge of flange to centroid of reinforcement (from the bottom flange). It is assumed that reinforcement exists both above and below the opening.

Web Opening Checks

Shear and moment strength checks are performed on the member according to the specifications outlined in AISC Design Guide 2: Steel and Composite Beams with Web Openings. The strength checks in the construction stage consider the beam alone, with no composite action. The strength checks in the final stage consider the member with composite action, unless the opening is in a position where the moment is negative.

In addition to strength checks, stability checks are performed on the member and reinforcement according to Design Guide 2 Section 3.7.a. With the exception of “Circular Openings” (Section 3.7.b.4), “Other Considerations” (Section 3.7.b) and “Additional criteria for composite beams” (Section 3.7.c) are not taken into consideration in the checks.

The formulas used to determine the reduced strength from the presence of the opening can be viewed for any member with an opening in the detailed output.

Construction Stage Flexural Strength Example:

Construction Stage Shear Strength Example:

Construction Stage Unity Check Example:

Final Stage Flexural Strength Example:

Final Stage Shear Strength Example:

Final Stage Unity Check Example: