PSI - Issue 64

Abheetha Peiris et al. / Procedia Structural Integrity 64 (2024) 588–595 Peiris, Harik, et.al. / Evaluation of Historic Truss Bridges 00 (2019) 000–000

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Capacity Factor ( Y 1 ) Geometric Factor ( Y 2 ) Safety Factor ( Y 3 )

RPF = Y 1 ꞏ Y 2 ꞏ Y 3 (3) The Capacity Factor, Y 1 , is based on a proposed rehabilitation effort’s capability to meet or exceed required load demands. It may be acceptable for a bridge to accommodate loads less than current design code driven standards. This would encompass the cost-efficient nature of the rehabilitation work as well as the effect of any rehabilitation efforts on the historical nature of the structure (Table 7).

Table 7. Capacity factor, Y 1

Potential for Rehabilitation to Improve Capacity

Factor Y 1

Capacity cannot be increased cost effectively or without affecting historical significance

1 2 3

Capacity can be increased, but not up to specification Sufficient capacity or can be increased up to or beyond demand

The Geometric Factor, Y 2 , evaluates the capacity of a rehabilitation effort to meet or exceed any geometric/functional needs. Rehabilitation actions falling within this category include widening of lanes and meeting clearance requirements, among others. The weights assigned for Y 2 are presented in Table 8.

Table 8. Geometric factor , Y 2

Potential for Rehabilitation to Improve Geometry

Factor Y 2

Geometry cannot be improved cost effectively, or without affecting historical significance Geometry can be improved, but not up to specifications Sufficient geometry or can be improved up to or beyond specifications

1 2 3

The Safety Factor, Y 3 , identifies how well rehabilitation can improve any safety-related issues. Safety improvements need to be carried out in a cost-effective manner without affecting the historic nature of a bridge, and they include corrective actions to road alignment, visibility, and any causes of traffic accidents, among others. Y 3 is presented in Table 9.

Table 9. Safety factor, Y 3

Potential for Rehabilitation to Improve Safety

Factor Y 3

Safety cannot be improved cost effectively, or without affecting historical significance Safety can be improved, but not up to specifications No safety issues or can be improved up to or beyond specifications a

1 2 3

5. Historic truss bridge rehabilitation prioritization The historic truss bridge rehabilitation prioritization database for the 94 bridges was developed using the Historical Impact Factor, HIF. 17 bridges were neither structurally nor functionally deficient, 35 bridges were categorized as Functionally Obsolete (FO), and the remaining 42 bridges were Structurally Deficient (SD). Figure 1 identifies the location of the 108 bridges considered in the study. Table 10 lists the number of bridges having the same HIF value. 8 bridges have an HIF greater than 100. Of the remaining bridges, 30 have an HIF between 10 and 100, while the rest have an HIF less than 10. In general, fewer bridges have the same HIF for large HIF values. The BCF and RPF factors were not used in this study, as the HIF offered sufficient clarity for investigating the rehabilitation potential of the bridges.