What is the difference between restrained and unrestrained beam

Figure 1b. Floor end restrained by welds to support for restrained test. Figure 1c. Floor end unrestrained resting on support for unrestrained test. AISC and AISI funded furnace testing of steel floor assemblies, which demonstrated that restraint from the furnace frame provided no fire resistance benefit in the specific cases tested.

This testing resulted in modifications to a specific UL listing D NIST performed furnace testing of steel trusses Figures 1a, b, and c and found that an unrestrained assembly achieved a higher fire resistance rating when compared to an equivalent restrained assembly. These test results demonstrate that the effect of restraint varies among different structural systems and restraint conditions, and cannot be easily simplified in practice, especially in a binary fashion. This section addresses structural fire protection by specifying the prescriptive approach as the default option for structural fire protection design.

When structural fire engineering is employed, analysis of structural system response inherently considers the amount of structural restraint that is actually present within a particular building design. However, when the prescriptive approach is used, the degree of restraint may be difficult for a designer to judge with a high level of confidence.

In light of this, designers may choose to take a conservative approach when classifying restraint conditions per ASTM E In all cases, the authority having jurisdiction may be consulted as to the proper interpretation for a given project. Clearly, there is a conflict between the boundary conditions and general limitations of standard furnace testing to represent realistic mechanical behavior, and the understanding of how structural systems actually perform under fire exposure.

Acknowledgment: The authors would like to thank Dr. Carter, F. Carter, C. Gross, J, et al. Post, N. Sep, By Kevin J. Can you provide a UL number approved on this type of structural member?

Reply 0. Related webinar Steel Protection An Overview of Fireproofing on Structural Steel Members There are various ways to protect exposed structural steel in the event of a fire, whether in an airport, shopping mall, or in a commercial building.

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