Appeal 14864

Table 601, 704.2 Column Protection-Individual encasement

Columns shall be fire resistance rated in accordance with OSSC Table 601. The required fire resistance rating of columns shall be 1 Hr. 704.2 requires entire column to be provided individual encasement protection on all sides.

The construction project is renovating the historic Towne Storage building in Portland, Oregon. The building is Type IIIA construction. The structure is fully protected by automatic sprinklers and a fire alarm system. The proposed column to be installed in the interstitial space between floors requires 1-hour fire-resistance per Table 601 of the OSSC. Fire resistance will be provided through equivalent surface fire protection coating per NTRL tested assemblies.

The proposed assembly with protection by intumescent coating of the steel members was evaluated against Y616 tested assemblies with fire caulking adding additional protection at the steel/wood interface. This covering thickness was supported by documentation dated 11-17-16 by an Isolatek application engineer. Per the attached EJ Letter developed by an Oregon Fire Protection Engineer, the assembly will meet the minimum fire resistance requirement per OSSC for this building.

Table 601, 704.3 Beam Protection-Individual encasement

Structural members shall have fire resistance ratings in accordance with OSSC Table 601. The required fire resistance rating of beam shall be 1-Hr. 704.3 requires entire beam to be provided individual encasement protection on all sides.

The construction project is renovating the historic Towne Storage building in Portland, Oregon. The building is Type IIIA construction. The structure is fully protected by automatic sprinklers and a fire alarm system. The proposed beam to be installed in the interstitial space between floors requires 1-hour fire-resistance per Table 601 of the OSSC. Fire protection is required per 704.3 and will be provided through equivalent surface fire protection coating per a NTRL tested assembly.

The proposed assembly utilizes intumescent coating of the steel in the assembly to provide 1- Hr fire resistance. The wide flange beam meets the test configuration per N634 (beam) with a prescribed thickness of 22 Mils. The wood ledger provides more than 1 hr of cover protection.
Per the attached EJ Letter developed by an Oregon Fire Protection Engineer, the assembly will meet the minimum fire resistance requirement per OSSC for this building.

703.2 Fire-resistance ratings.

703.2 Fire-resistance ratings. The fire-resistance rating of building elements, components or assemblies shall be determined in accordance with the test procedures set forth in ASTM E 119 or UL 263 or in accordance with Section 703.3. Where materials, systems or devices that have not been tested as part of a fire-resistance-rated assembly are incorporated into the building element, component or assembly, sufficient data shall be made available to the building official to show that the required fire-resistance rating is not reduced. Materials and methods of construction used to protect joints and penetrations in fire-resistance-rated building elements, components or assemblies shall not reduce the required fire-resistance rating.

Historic Towne Storage building in Portland, Oregon is being renovated. The existing building is of Type IIIA construction. The floor/ceiling beams of this building are required to be 1-hour fire-resistance rating, per Table 601 of the OSSC.

A 6 ¾ x 13 ½ Glulam beam is connected to a round steel column by a 3/8” x 8 ¼” x 11” steel plate. The Glulam beam was established as a 1 hour rated per another appeal. This appeal is only to establish the protection required for the steel plate connection between the 1 hour wood beam and the 1 hour steel column.

An Engineering analysis as permitted by OSSC 703.3 prepared by an Oregon licensed Fire Protection Engineer is attached to establish equivalent protection for the steel connector plate. The analysis is based on steel beam tested per ASTM E119 test and certified by UL laboratories as design UL N634.

This building renovation project needs to use custom designs and innovative structural strategies due to the unique nature of the existing elements in this historical building. Additionally, fire resistance of timber wood members, such as the beam used here, is determined using the NDS Guide, which does not address the steel plates and through bolts used to connect the Glulam beam to the steel column. Therefore an engineering judgment is required to bridge the gap.

The attached Engineering Judgment (EJ) used the weakest member in the assembly, 3/8” vertical steel plate, and followed the Engineering analysis method prescribed by OSSC 703.3. This steel plate was compared to the smallest steel beam of UL assembly N634 and appropriate adjustments were made to accommodate the W/D ratio differences between the two. Applying equations established by the Society for Fire Protection Engineers (SFPE) for such analysis and using manufacturer’s published data regarding the intumescent material’s performance under fire conditions, we determined the minimum thickness for the intumescent materials to achieve at least 1 hour fire resistive rating for these connectors and documented it in the attached Engineering Judgment.

The steel connectors when protected per the attached EJ developed by an Oregon Fire Protection Engineer, will meet the minimum 1 Hr. fire resistance requirement of OSSC for this building. Therefore we urge you to approve this appeal.

Table 601, 704.3 Beam Protection-Individual encasement

704.3 Fire-resistance ratings. The fire-resistance rating of building elements, components or assemblies shall be determined in accordance with the test procedures set forth in ASTM E 119 or UL 263 or in accordance with OSSC. Where materials, systems or devices that have not been tested as part of a fire-resistance-rated assembly are incorporated into the building element, component or assembly, sufficient data shall be made available to the building official to show that the required fire-resistance rating is not reduced. Materials and methods of construction used to protect joints and penetrations in fire-resistance-rated building elements, components or assemblies shall not reduce the required fire-resistance rating.

Historic Towne Storage building in Portland, Oregon is being renovated. The existing building is of Type IIIA construction. The floor/ceiling beams of this building are required to be 1-hour fire-resistance rating, per Table 601 of the OSSC.

A steel W flange beam is proposed to be protected by a combination of intumescent coating and sacrificial wood encasing. The proposed design of the attachments are to be 1 hour fire resistant rated with equivalent protection per a NTRL tested assembly.

An Engineering analysis as permitted by OSSC 703.3 prepared by an Oregon licensed Fire Protection Engineer is attached to establish equivalent protection using wood and intumescent coating to protect the steel beam. The intumescent coating thickness is determined by the analysis of a steel beam tested per ASTM E119 test and certified by UL laboratories as design UL N634. The wood protection members are analyzed using the AWC NDS guide.

This building renovation project has to use custom designs and innovative structural strategies due to the unique nature of the existing elements in this historical building. The existing steel beam is reinforced by bolting 4x8 heavy timber wood members. These members are bolted to the steel beam. The exposed surfaces of the steel beam and the steel bolts used to attach the HT wood to the steel beam need protection to maintain the 1 hour rating. There are no tested assemblies in this configuration, therefore we have completed an engineering analysis to establish the protection needed.

The bottom of the steel beam not covered by wood elements is protected by intumescent coating per UL Design N634. The rest of the steel beam surfaces are protected by a HT wood member, sacrificial 2x rough sawn timber is added to protect the beam through bolts. Heavy timber members are inherently fire resistance. The exposed steel bolts will be protected by the encasing it by 2x rough sawn sacrificial wood members per AWC NDS TR10 guide.

The analysis follows the tested steel beam protection per UL N634 for the required intumescent coating thickness. Additional, fire caulking is required at the steel/wood interface to ensure the steel member edge will be protected at that junction.

This is a conservative approach as the UL E119 test member would be exposed to heating on all faces, while our assembly can only be exposed to heat from a fire on one face with significant wood protection on all other surfaces. The steel beam when protected per the attached EJ developed by an Oregon Fire Protection Engineer, will meet the minimum 1 Hr. fire resistance requirement of OSSC for this building. Therefore we urge you to approve this appeal.

713.4 Shaft wall fire barriers. 1009.3.1.2 Stairway Fire Resistance,

OSSC 713.4 and 1009.3.1.2 require fire barrier assemblies of 2 hours for this building.

The shaft walls are unique compared to other interior fire rated walls, they are often rectilinear in plan and tied together The rectangular shape affords improved stability and hence allows these to perform better in a fire scenario compared to a straight wall, which can buckle or bend under these conditions.

The wall itself is a listed 2 hour assembly and does not need any modification. The extension of the one inch liner panel along the interior of the shaft ensures continuous protection from fire exposure on that side. The addition of wood fire blocking ensures that fire cannot break through the edge of the wall and the floor assembly from the building side. The wood blocking is evaluated using the American Wood Council NDS standards and established as being capable of resisting a fire in excess of 2 hours.

The junction of the 2 hour wall assembly and fire rated floor, when protected with the continuous wood blocking and extension of the interior liner panel, per the attached EJ Letter developed by an Oregon Fire Protection Engineer, will meet the minimum fire resistance required by OSSC for this building.