AS 5100.5:2017

AS 5100.5:2017 contains the only explicit assessment-level provisions in any Australian Standard concrete code — Section 14, which provides guidance for the structural assessment of existing concrete bridges. This makes the standard significant beyond bridge engagements: TRSC routinely cites AS 5100.5 Section 14 as the closest Australian-Standard parallel to ASCE 41 or Eurocode 8 Part 3 assessment frameworks, and applies its principles (with documented engineering judgement) to non-bridge existing concrete structures where AS 3600 is silent on assessment. Three application points matter for existing-asset practice. First, AS 5100.5 durability provisions are more rigorous than AS 3600 because of the 100-year design life and the typical aggressive exposure of bridge structures (marine, saline, freeze-thaw at elevated locations). For existing concrete bridges under continuing-life recertification, the assessment compares measured chloride profile and carbonation depth to the AS 5100.5 durability acceptance criteria — and where the measured values indicate durability failure, the assessment quantifies the residual life and the intervention pathway required to extend life to the desired horizon. The Saltwater Creek bridge investigation used AS 5100.5 durability provisions applied to chloride-profile and carbonation-depth measurements to derive a 30-year residual life with specified ongoing maintenance, rather than the immediate full replacement that conservative desktop assessment would have recommended. Second, AS 5100.5:2017 incorporated the AS 3600:2009 MCFT-based shear and punching shear provisions, which represent a methodological change from earlier editions. Pre-2017 bridge structures designed under earlier editions have shear capacities calculated using empirical formulations that can be unconservative for high-strength concrete or thin-section elements. TRSC's bridge-element shear capacity reassessment is most commonly decision-controlling on prestressed-concrete I-beams, deck slabs at column-head punching shear, and post-tensioned slabs at edge connections. Third, AS 5100.5 post-tensioning provisions (Section 8) are critical for existing post-tensioned bridge assessment, particularly in Queensland where post-tensioned bridge construction was widespread from the 1970s onwards. Tendon protection condition (grouting voids, corrosion of tendons, anchorage condition) is the dominant risk for these structures, and the standard's post-tensioning durability and assessment provisions are the basis for inspection methodology, residual-capacity calculation, and remediation specification. TRSC's post-tensioned bridge assessments include borescope inspection of tendon ducts at strategic locations, vibration-based tendon-tension verification, and explicit residual-capacity calculation accounting for any identified tendon section loss. The standard's Section 14 assessment provisions support these methodologies and provide the codified framework for the resulting Form 15 certification.