Appeal 14850

722.2.4.2 Minimum cover for R/C columns.

The minimum thickness of concrete cover to the main longitudinal reinforcement in columns, regardless of the type of aggregate used in the concrete and the specified compressive strength of concrete, f 'c, shall not be less than 1 inch (25 mm) times the number of hours of required fire resistance or 2 inches (51 mm), whichever is less.

Six existing columns are located along j4 column line on the south sides of the hearing rooms. The 20x20 columns exceed a 4 hr rating per OSSC §722.2.4, but the minimum existing concrete cover over columns is only 1 inch. Additional fire resistance will be provided through equivalent surface fire protection coating per NTRL tested assemblies.

The R/C column is required to be 3-hour fire-resistance rated per OSSC Table 601. The Column is 20x20, exceeding the minimum dimension per 722.2.4, but the concrete cover provided does not meet the prescriptive requirements of 722.2.4.2 to achieve a 3-hour rating. In lieu of increasing concrete cover thickness, additional fire protection will be provided by intumescent coating.
Based on the size of the member and the addition of cover protection proposed, the concrete column assembly will exceed the required 3 hr rating with the minimum 2 hr cover.
The detailed evaluation of fire rating for the member is provided in a separate Engineering Judgement letter (EJ#1A) produced by an Oregon Registered Fire Protection Engineer.

721.5.1 Fire Resistance for Structural Steel Columns.

The Fire-resistance rating of steel columns shall be based on the size of the element and the type of protection provide in accordance with this section.

Six existing 20x20 concrete columns located along j4 column line on the south sides of the hearing rooms will be supplemented with adjacent new steel columns to form a new assembly. Passive fire Protection requirements of the steel were compared to code minimum requirements of OSSC Table 601. The steel will be protected with Intumescent coating per UL design testing to achieve 3 hr rating.
The detailed applied fire proofing evaluation for the steel member is provided in the attached Engineering Judgement letter produced by an Oregon Registered Fire Protection Engineer.

The new steel columns are comprised of significantly thicker steel than the compared UL tested assemblies which provide greater intrinsic fire resistance. Once the added fire protection coating is applied, the members will maintain a greater fire resistance rating than prescriptive requirement.
Therefore, it is our opinion that the proposed protection for the steel column assembly will exceed the required 3 hr rating per Table 601 as compared and detailed in this letter with UL fire testing guidance.
The detailed evaluation of fire rating for the member is provided in a separate Engineering Judgement letter (EJ#1B) produced by an Oregon Registered Fire Protection Engineer.

722.2.4.2 Minimum cover for R/C columns.

The minimum thickness of concrete cover to the main longitudinal reinforcement in columns, regardless of the type of aggregate used in the concrete and the specified compressive strength of concrete, f 'c, shall not be less than 1 inch (25 mm) times the number of hours of required fire resistance or 2 inches (51 mm), whichever is less.

Several existing (stand-alone) concrete columns are located along grids j4 and j8. See attached plan diagrams for relevant locations. The 20x20 columns exceed a 4 hr rating per OSSC §722.2.4, but the minimum existing concrete cover over columns is only 1 inch. These columns will be protected with SFRM to achieve a 3-hour minimum fire resistance rating.

The R/C column is required to be 3-hour fire-resistance rated per OSSC Table 601. The Column is 20x20, exceeding the minimum dimension per 722.2.4, but the concrete cover provided does not meet the prescriptive requirements of 722.2.4.2 to achieve a 3-hour rating. In lieu of increasing cover thickness, additional fire protection will be provided by SFRM.
The detailed evaluation of fire rating for the column is provided in a separate Engineering Judgement letter (EJ#2A) produced by an Oregon Registered Fire Protection Engineer.

721.5.1 Fire Resistance for Structural Steel Columns.

The Fire-resistance rating of steel columns shall be based on the size of the element and the type of protection provide in accordance with this section.

Several new steel columns will be added to the Jefferson Station structure. See attached plan diagrams. Passive fire Protection requirements of the steel were compared to code minimum requirements of OSSC Table 601. The steel will be protected with SFRM per UL design testing to achieve 3 hr rating.
The detailed applied fire proofing evaluation for the steel member is provided in a separate Engineering Judgement letter produced by an Oregon Registered Fire Protection Engineer.

The new steel columns are compared UL tested assemblies and provide equivalent fire resistance. Once the fire protection coating is applied, the members will maintain a greater fire resistance rating than the prescriptive requirement.
The proposed protection for the steel column assembly will exceed the required 3 hr rating per Table 601 as compared and detailed in this letter with UL fire testing guidance.
The detailed evaluation of fire rating for the member is provided in a separate Engineering Judgement letter (EJ#2B) produced by an Oregon Registered Fire Protection Engineer.