## Function

- Select the Load Rating Parameter for Steel Bridge Load Rating design.

## Call

From the main menu, select **[Rating] tab > [Type : Steel Bridge] > [Steel Bridge : AASHTO] > [Rating Input Data] group > [Rating Parameters] >**** [Rating Parameters]**

## Input

### System Factor

Input the System Factor to be applied to the normal resistance, which reflects the level of the complete superstructure system.

### Strength Limit State

Check on to perform load rating in strength limit state.

**Strength Resistance Factor**

**Girder Type for Box/Tub Section**

**Single Box Sections **: If the Single Box Sections option is selected, St.Venant torsion and distortion stresses need to be taken into account. The value of distortion stress is determined based on the input value of "Warping Stress Range" option in Fatigue Parameter.

**Multiple Box Sections**

**Consider St.Venant Torsion and Distortion Stresses **: Check on to consider St.Venant torsion in accordance with distortion stress. In case of multiple box sections, St.Venant torsion and distortion stresses may be neglected if the relevant conditions (Article 6.11.2.3) are satisfied. The value of distortion stress is determined based on the input value of "Warping Stress Range" option in Fatigue Parameter.

**Option for Strength Limit State**

**Appendix A6 for Negative Flexure Resistance in Web Compact/Noncompact Sections **: Check on to apply Appendix A6 for the flexure strength of straight composite I-sections in negative flexure with compact/ noncompact webs. Use of Appendix A6 is optional in accordance with the code.

**Mn≤1.3RhMy in Positive Flexure and Compact Sections(6.10.7.1.2-3) **: If the three conditions below are not satisfied for the compact sections under positive flexure in a continuous span, the Mn value is restricted to 1.3RhMy.

- The span under consideration and all adjacent interior pier sections satisfy the requirements of Article B6.2,

- The appropriate value of θRL from Article B6.6.2 exceeds 0.009 radians at all adjacent interior-pier sections

- In which case the nominal flexural resistance of the section is not subject to the limitation of Eq. 6.10.7.1.2-3.

**Post-buckling Tension-field Action for Shear Resistance (6.10.9.3.2) **: Check on to consider post buckling resistance due to tension field action in the nominal shear resistance of an interior stiffened web panel.

### Service Limit State

Check on to perform load rating in strength limit state.

**Limiting Stresses in Structural Steel**

**Auto-Calculation**

**Design Load **: fR = 0.95 RhFyf

**Legal/Permit Load **: fR = 0.95 Fyk

**User Input**

**Design Load**

**Compressive stress** : Input the limit state compressive stress.

**Tensile stress **: Input the limit state tensile stress.

**Legal/Permit Load**

**Compressive stress **: Input the limit state compressive stress.

**Tensile stress **: Input the limit state tensile stress.

### Fatigue Limit State

Check on to perform load rating in fatigue limit state

**Fatigue Life Check** (When AASHTO-LRFR19 is selected as rating code)

**Only infinite fatigue life **: Rating check is done just to verify the infinite fatigue life.

**Infinite and finite fatigue life** : Rating check is done for infinite fatigue life. If the life of the detail is finite, then finite life and serviceability index are provided.

**Finite Fatigue Life Parameter**

**Current age of the detail, a **: Current age of the detail being rated in years.

**Expected Annual Growth Rate of ADTT_SL, g **: Expected annual growth rate of the average number of trucks per day in a single lane. Input in decimal form, e.g., if growth rate is 2%, input 0.02.

**(ADTT_SL)limit **: Highway design maximum average number of trucks per day in a single lane for the roadway under consideration.

**(ADTT_SL)0 **: Average number of trucks per day in a single lane in the first year the detail was in service.

**Fatigue Serviceability Index**

**Load Path Factor, G** : Load path factor as given in Table 7.2.6.1-1, Manual for bridge evaluation, Third edition

**Redundancy Factor, R **: Redundancy factor as given in Table 7.2.6.1-2, Manual for bridge evaluation, Third edition

**Importance Factor, I** : Importance factor as given in Table 7.2.6.1-31, Manual for bridge evaluation, Third edition

### Application of Diagnostic Test Result

**Load Measurement** : Adjustment factor resulting from the comparison of measured test behavior with the analytical model can be calculated. Select between Strain and Displacement obtained from the diagnostic test. Measured value can be entered in Diagnostic Test Results menu.