Floor Beam Load Rating T [SIG]

The floor beam load rating template collects the inputs that stay constant across every LRFR floor beam load rating — the mapped strength and service load rating combinations, the condition, system and resistance factors, the modular ratio, and the construction type. Each individual floor beam load rating object (under the Load Rating section) points at one template, so these values do not have to be repeated at every floor beam.

General

Strength (Load Rating Combination): The load rating combination table serves as the basis for all finite element analysis results used in the load rating equations. Pick the Load Rating Combination Table that maps the analysis result cases (DC1, DC2, DW, and the Design, Legal, Emergency, and Permit live-load cases) and their load factors for the strength limit state. The user must provide a value.

Service (Load Rating Combination): The load rating combination table serves as the basis for all finite element analysis results used in the load rating equations. Pick the Load Rating Combination Table that maps the analysis result cases and their load factors for the service limit state. The user must provide a value.

Condition Factor: Condition factor φc per AASHTO MBE Article 6A.4.2.3, based on the condition state of the floor beam per the most recent inspection report. Typical values: 1.00 for good or satisfactory condition, 0.95 for fair condition, and 0.85 for poor condition. The value must be greater than zero for a rating factor to be computed.

System Factor: System factor φs per AASHTO MBE Article 6A.4.2.4, reflecting the redundancy of the floor system. The default of 0.85 corresponds to MBE Table 6A.4.2.4-1 for floor beams spaced more than 12 ft apart with noncontinuous stringers; use a higher value where the floor system provides more redundancy. The system factor is applied to flexure only; shear is rated with a system factor of 1.0 (MBE 6A.4.2.4). The value must be greater than zero.

Resistance Factor for Flexure: Resistance factor φf applied to the nominal flexural resistance of the floor beam. The default of 1.0 is the AASHTO LRFD Article 6.5.4.2 value for flexure of steel members. The value must be greater than zero.

Resistance Factor for Shear: Resistance factor φv applied to the nominal shear resistance of the floor beam. The default of 1.0 is the AASHTO LRFD Article 6.5.4.2 value for shear of steel members. The value must be greater than zero.

Modular Ratio Comp. Method [EsbyEc/User Input]: Selects how the modular ratio n used for the composite section properties is obtained. EsbyEc computes n as the elastic modulus of the steel divided by the elastic modulus of the deck concrete. User Input uses the value entered in Modular Ratio. The modular ratio only matters for floor beams that act compositely with the deck.

Modular Ratio: The modular ratio n used in the transformed composite section calculations when Modular Ratio Comp. Method is User Input (default 8). It must be greater than zero. Available when Modular Ratio Comp. Method is User Input.

Type of Construction [Shored Construction/Unshored Construction]: With Unshored Construction, permanent load applied before the concrete deck has hardened or become composite is carried by the steel section alone, while permanent load and live load applied afterwards are carried by the composite section. With Shored Construction, all permanent load is assumed to be applied after the deck has become composite.

Use Deck Rebar in Plastic Mom. Calc. (Pos. Flex.) [Yes/No]: Controls whether the deck reinforcement forces (Prt and Prb) are included when computing the plastic moment of a composite floor beam in positive flexure. When set to Yes, the deck reinforcement contributes to the plastic moment capacity; when set to No, it is conservatively neglected.