Questions about this article, topic, or product? Click here.

Connection Tags in STAAD.Pro

One of the features added to STAAD.Pro V8i in the SELECTseries 4 (build 20.07.09) release was the implementation of a system to allow a STAAD model to be marked with connection tags. Connection tags allow you to assign a suitable connection types for a steel frame structure which can be passed on to a detailer as they are included in an ISM repository. You can check basic connection capacities utilizing suitable externally supplied capacity data for moment or shear connections. Simply analyze your model to get the internal forces, which are then compared to the capacities for the connection type and section sizes used.

Member end releases, which are of course used to model the end connections for a member, can be assigned during the process of assigning connection tags so the modeled data agrees with the data passed on to a detailer. However, if you already have member end releases assigned for your model, you can skip re-assigning them along with the connection tags.

An external XML file is used to store capacity data for a given connection tag and members in a connection (beam and column). Checks for either moment or shear, both including axial effets, are displayed as a tabular report. The XML file is completely configurable and additional connection tags and capacity values can be added at any time. Refer to the online help for a detailed explination of the XML schema.

Tip: XML is a "self-describing" file format and, as such, the open/close elements and attributes are all in English and stored as plain text, so that any text editor software can be used to open and edit this file. Care should be taken to make sure the XML remains complete and valid. An XML-aware text editor - such as the free Notepad++ with the XML Tools plug-in - is recommened.

Once you've assigned connection tags and checked capacities to ensure they are adequate, you can pass on this data to a detailer along the rest of your STAAD.Pro model. To do so, create or update an ISM repository. You can verify that the connection data is not stored in the repository using Structural Synchronizer.

Note: Using the basic connection tag capacity check allows you to rapidly check assigned connection tags. To perform a detailed connection design or check, please use the RAM Connection tab in the STAAD.Pro interface.

Rules Used for Checking Connection Capacity

The connections capacity can be checked based on demand for a given selected of loads once the structure has been analyzed. The checks are dependent upon whether the connection is specified as a moment or shear connection.

Moment Connections

Shear Capacity Check

The shear capacity for a given beam/column combination provided in the ConnectionTagFile.xml file is checked against the demand taken as the absolute value of the major axis shear value, Fy, from each of the load cases included and the maximum value reported.

For example, if the shear capacity in the XML file = 207.345 kN:

If FY = ±208.000 kN, then demand = 208.00 > 207.345, therefore the connection fails
If FY = ±200.000 kN, then demand = 200.00 < 207.345, therefore the connection passes

Moment Capacity Check

The moment capacity check for a given beam/column combination is based on both the major axis moment, Mz, and axial force, Fx. For each load case, the maximum demand is determined from the end moment plus the axial force multiplied by the tension force factor, alpha, and compared against the given moment capacity value. Thus, demand = |Mz| + α|Fx|

For example, if the moment capacity from the XML file = 35.951 kN⋅m and the tension force factor, alpha = 0.09695:

If Mz = 30 kN⋅m and Fx = -50 kN, then demand = 30 + 50(0.09695) = 34.8475 kN⋅m < 35.951 kN⋅m, therefore the connection passes
If Mz = 32 kN⋅m and Fx = 50 kN, then demand = 32 + 50(0.09695) = 36.8475 kN⋅m >35.951 kN⋅m, therefore the connection fails

Shear Connections

The shear capacity for a given beam/column combination provided in the ConnectionTagFile.xml file is checked against the demand taken as the major axis shear value, Fy, and a proportion of the axial force from each of the load cases included and the maximum value reported. Thus, demand = |Fy|+ α|Fx|

For example, if the shear capacity from the XML file = 15.538 kN and the tension force factor, alpha = 0.2016:

If Fy = 12 kN and Fx = -25 kN, then demand = 12 + 25(0.2016) = 17.04 kN > 15.538 kN, therefore the connection fails
If Fy = -10 kNm and Fx = 25 kN, then demand = 10 + 25(0.2016) = 15.04 kN < 15.538 kN, therefore the connection passes

Note: Moment capacity is not checked for a shear connection tag.

Connection Tags in Action

In this video, STAAD.Pro Product Manager, Carlos Aguera, demonstrates how to create and assign connection tags, check connection capacity, and create an ISM repository for passing on data to a detailer. He also briefly reviews the data structure of the connection tag XML file and how to locate it on your computer.