Bridges can be subject to fire damage for several reasons including vehicle accidents (on or below), arson, accidental fires, or even wildfires. In more extreme cases, a bridge can be permanently weakened and potentially collapse. Given the probability of bridge fires is continually increasing with ever-growing traffic volume and bridge numbers, guidelines for timely damage assessment and repair options should be researched and developed. Several cases of bridge fires have occurred in recent history. These cases not only highlight the unpredictable nature of bridge fires, their cause, and their damage, but also gives reason for further research to mitigate their effects immediate to the bridge and also to the bridge users. Regardless of the reason, intentional or accidental, the hardship is for the traveling public to bear as a bridge removed from commission unexpectedly can be cause for traffic delays and overall economic strain. Some research studies have been completed with respect to fire-damage assessment and their causes, but are generally limited to what can be concluded from visual observation and paper studies. Damage assessment completed through visual observation followed by strength and serviceability testing is rare.

The primary objective will be to gain technical information related to the evaluation, repair or replacement of concrete and steel girders after being subjected to fire. Specifically, the goals will be to: 1. Assess capacity of fire-damaged girders, explore girder repair options, and develop repair guidelines 2. Investigate material properties and residual capacities of fire damaged bridges 3. Evaluate protection methods

The work plan is described in three primary phases. Phase 1 is an evaluation of residual capacity after fire exposure, an exploration of girder repair options, and development of repair option guidelines. Phase 2 is an in-depth investigation of material properties while being subjected to fire and the prediction of residual capacities of fire-damaged bridges using finite element analysis. Phase 3 is an evaluation of protection methods. Phase 1 (est. $300,000) Phase 1 consists of load testing full-scale concrete, steel, and timber girders that have been subjected to fire to assess the capacity with respect to their calculated capacity. Additionally, an exploration of various repair options will be completed for concrete, steel, and timber girder bridges where the capacity has been reduced but long-term adequacy is not a concern with properly completed repairs. Economic feasibility will be a major consideration for any repair options identified and this work will consist of the development of lifecycle cost models to aid in decision-making. A supplementary document specifically guiding the repair options for concrete, steel, and timber girder bridges will be developed. This document will provide summaries, commentary, and other important information that will clearly guide the decision for repair of fire-damaged girders. Tasks: 1. Literature review 2. Load test fire-damaged concrete, steel, and timber girders. 3. Identify the best repair options for concrete, steel, and timber girders, while considering the economic feasibility. 4. Assess the performance of repaired girders by completing load testing of girders first subjected to damage and subsequently repaired. 5. Develop guide for completing the best repair options identified in Tasks 2 and 3. Phase 2 (est. $250,000) Phase 2 consists of conducting a program of laboratory tests to aid in the assessment and quantification of fire damage within multiple separate areas of focus: 1) concrete-only, 2) concrete with pre-stressing strands, 3) steel and 4) timber and to subsequently develop finite element models of 1) concrete girder, 2) steel girder, and 3) timber girder bridges using the material strength results obtained. Tasks: 1. Literature review 2. Evaluation of strength of small-scale specimens subjected to load and temperature variations: concrete-only, pre-stressed concrete, steel, and timber. 3. Prediction of residual capacities through the development of finite element models for concrete, steel, and timber girders incorporating material strength properties identified during Task 2. Phase 3 (est. $200,000) Phase 3 consists of investigating options for fire-proofing or increasing fire-resistance for new and existing bridges and to assess the efficacy of these options. This portion of the work will also consider the development of agency guidelines for providing a policy for joint use agreement guidance on under bridge parking or usage to prevent fire. Tasks: 1. Literature Review 2. Identify options for fire-proofing or adding fire-resistance to concrete, steel, and timber girders. 3. Produce specimens with added fire-proofing and assess the performance against non-fire-proofed control specimens. 4. Produce guide document for best fire-proofing/fire-resistance practices of bridge girders. Expansion to this pooled fund study originated from an on-going Iowa DOT SPR Project 20-SPR2-003 focusing on an incident near Sioux City, Iowa. The relevant parts of that proposal are attached below.

Desired total commitment from each partner is $100,000 split between FY21-25. This can be accomplished through 4 years at $25,000, 5 years at $20,000 or another combination. Commitment covers travel for an in-person meeting approximately once per year throughout the life of the project. Specific meetings and locations to be determined during the project. Will be pursuing a 100% SPR Part B waiver. Additional partners are always welcome. Please reach out to the Lead Agency Contact at any time.