> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/truss-bridge-workflow/combinations-tb/design-load-combinations-tb/load-rating-combination-table-lfd-tb.md). # Load Rating Combination Table (LFD) \[TB] The Load Rating Combination Table (LFD) maps the analysis result stages (dead, design, legal, emergency, and permit live loads) to the AASHTO Load Factor Rating (LFR) load factors used by every LFD-rated element — truss members, girders, and floor beams. Each Load Rating (LFD) template points at one of these tables to inherit the factors and stages, so the combination is defined once and reused across all members. Unlike the LRFR table (which uses γ factors and a min/max dead-load envelope), the LFD table uses a single dead-load factor A1 and a live-load factor A2 per the Manual for Bridge Evaluation Part 6B. ## Dead Load The dead-load stages stay separate (moment and shear are pulled per stage), but a single LFD factor is applied — there is no min/max envelope. **A1 (DC, Dead Load Factor):** The LFR dead-load factor applied to the structural dead load (DC1 + DC2). Per MBE Part 6B this is 1.3. **DC1:** Pick the analysis case (construction stage) that carries the first structural dead-load component (e.g. the non-composite steel self-weight). **DC2:** Pick the analysis case that carries the second structural dead-load component (e.g. composite superimposed dead load). **A1 (DW, Wearing Surface Factor):** The LFR dead-load factor applied to the wearing surface / utilities (DW). Per MBE Part 6B this is 1.3. **DW:** Pick the analysis case that carries the wearing-surface (DW) dead load. ## Design Load **A2 (Design LL, Inventory):** The LFR live-load factor for the Inventory rating level (HS-20 design vehicle). Per MBE Part 6B this is 2.17. **A2 (Design LL, Operating):** The LFR live-load factor for the Operating rating level. Per MBE Part 6B this is 1.3. **LL:** Pick the analysis case that carries the design (HS-20) live load. ## Legal Load Up to 20 legal live-load stages, each rated separately. For every stage there is a factor (A2) and an analysis case; leave a stage's case empty to skip it. **A2 LL 1:** The legal live-load factor for stage 1. The default is 1.3. **LL 1:** Pick the analysis case for the legal live-load stage 1. Only stages whose case is set are rated. **A2 LL 2:** The legal live-load factor for stage 2. The default is 1.3. **LL 2:** Pick the analysis case for the legal live-load stage 2. Only stages whose case is set are rated. **A2 LL 3:** The legal live-load factor for stage 3. The default is 1.3. **LL 3:** Pick the analysis case for the legal live-load stage 3. Only stages whose case is set are rated. **A2 LL 4:** The legal live-load factor for stage 4. The default is 1.3. **LL 4:** Pick the analysis case for the legal live-load stage 4. Only stages whose case is set are rated. **A2 LL 5:** The legal live-load factor for stage 5. The default is 1.3. **LL 5:** Pick the analysis case for the legal live-load stage 5. Only stages whose case is set are rated. **A2 LL 6:** The legal live-load factor for stage 6. The default is 1.3. **LL 6:** Pick the analysis case for the legal live-load stage 6. Only stages whose case is set are rated. **A2 LL 7:** The legal live-load factor for stage 7. The default is 1.3. **LL 7:** Pick the analysis case for the legal live-load stage 7. Only stages whose case is set are rated. **A2 LL 8:** The legal live-load factor for stage 8. The default is 1.3. **LL 8:** Pick the analysis case for the legal live-load stage 8. Only stages whose case is set are rated. **A2 LL 9:** The legal live-load factor for stage 9. The default is 1.3. **LL 9:** Pick the analysis case for the legal live-load stage 9. Only stages whose case is set are rated. **A2 LL 10:** The legal live-load factor for stage 10. The default is 1.3. **LL 10:** Pick the analysis case for the legal live-load stage 10. Only stages whose case is set are rated. **A2 LL 11:** The legal live-load factor for stage 11. The default is 1.3. **LL 11:** Pick the analysis case for the legal live-load stage 11. Only stages whose case is set are rated. **A2 LL 12:** The legal live-load factor for stage 12. The default is 1.3. **LL 12:** Pick the analysis case for the legal live-load stage 12. Only stages whose case is set are rated. **A2 LL 13:** The legal live-load factor for stage 13. The default is 1.3. **LL 13:** Pick the analysis case for the legal live-load stage 13. Only stages whose case is set are rated. **A2 LL 14:** The legal live-load factor for stage 14. The default is 1.3. **LL 14:** Pick the analysis case for the legal live-load stage 14. Only stages whose case is set are rated. **A2 LL 15:** The legal live-load factor for stage 15. The default is 1.3. **LL 15:** Pick the analysis case for the legal live-load stage 15. Only stages whose case is set are rated. **A2 LL 16:** The legal live-load factor for stage 16. The default is 1.3. **LL 16:** Pick the analysis case for the legal live-load stage 16. Only stages whose case is set are rated. **A2 LL 17:** The legal live-load factor for stage 17. The default is 1.3. **LL 17:** Pick the analysis case for the legal live-load stage 17. Only stages whose case is set are rated. **A2 LL 18:** The legal live-load factor for stage 18. The default is 1.3. **LL 18:** Pick the analysis case for the legal live-load stage 18. Only stages whose case is set are rated. **A2 LL 19:** The legal live-load factor for stage 19. The default is 1.3. **LL 19:** Pick the analysis case for the legal live-load stage 19. Only stages whose case is set are rated. **A2 LL 20:** The legal live-load factor for stage 20. The default is 1.3. **LL 20:** Pick the analysis case for the legal live-load stage 20. Only stages whose case is set are rated. ## Emergency Load Up to 10 emergency-vehicle live-load stages, each rated separately. For every stage there is a factor (A2) and an analysis case; leave a stage's case empty to skip it. **A2 LL 1:** The emergency live-load factor for stage 1. The default is 1.3. **LL 1:** Pick the analysis case for the emergency live-load stage 1. Only stages whose case is set are rated. **A2 LL 2:** The emergency live-load factor for stage 2. The default is 1.3. **LL 2:** Pick the analysis case for the emergency live-load stage 2. Only stages whose case is set are rated. **A2 LL 3:** The emergency live-load factor for stage 3. The default is 1.3. **LL 3:** Pick the analysis case for the emergency live-load stage 3. Only stages whose case is set are rated. **A2 LL 4:** The emergency live-load factor for stage 4. The default is 1.3. **LL 4:** Pick the analysis case for the emergency live-load stage 4. Only stages whose case is set are rated. **A2 LL 5:** The emergency live-load factor for stage 5. The default is 1.3. **LL 5:** Pick the analysis case for the emergency live-load stage 5. Only stages whose case is set are rated. **A2 LL 6:** The emergency live-load factor for stage 6. The default is 1.3. **LL 6:** Pick the analysis case for the emergency live-load stage 6. Only stages whose case is set are rated. **A2 LL 7:** The emergency live-load factor for stage 7. The default is 1.3. **LL 7:** Pick the analysis case for the emergency live-load stage 7. Only stages whose case is set are rated. **A2 LL 8:** The emergency live-load factor for stage 8. The default is 1.3. **LL 8:** Pick the analysis case for the emergency live-load stage 8. Only stages whose case is set are rated. **A2 LL 9:** The emergency live-load factor for stage 9. The default is 1.3. **LL 9:** Pick the analysis case for the emergency live-load stage 9. Only stages whose case is set are rated. **A2 LL 10:** The emergency live-load factor for stage 10. The default is 1.3. **LL 10:** Pick the analysis case for the emergency live-load stage 10. Only stages whose case is set are rated. ## Permit Load Up to 5 permit live-load stages, each rated separately. For every stage there is a factor (A2) and an analysis case; leave a stage's case empty to skip it. **A2 LL 1:** The permit live-load factor for stage 1. The default is 1.3. **LL 1:** Pick the analysis case for the permit live-load stage 1. Only stages whose case is set are rated. **A2 LL 2:** The permit live-load factor for stage 2. The default is 1.3. **LL 2:** Pick the analysis case for the permit live-load stage 2. Only stages whose case is set are rated. **A2 LL 3:** The permit live-load factor for stage 3. The default is 1.3. **LL 3:** Pick the analysis case for the permit live-load stage 3. Only stages whose case is set are rated. **A2 LL 4:** The permit live-load factor for stage 4. The default is 1.3. **LL 4:** Pick the analysis case for the permit live-load stage 4. Only stages whose case is set are rated. **A2 LL 5:** The permit live-load factor for stage 5. The default is 1.3. **LL 5:** Pick the analysis case for the permit live-load stage 5. Only stages whose case is set are rated. --- # Agent Instructions This documentation is published with GitBook. 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