Evaluation of the long-term residual safety of a reinforced concrete bridge: a case study

Abstract

The present work proposes a comprehensive study of the safety evaluation of a reinforced concrete bridge in terms of the actual and expected degradation status. A bridge constructed in the early 1930s over the Cassibile River in Sicily, Italy, is selected for consideration. The study starts with a safety assessment based on the original design codes in use at the time of construction and then follows, by an exegetical approach, the evolution over time of the prescribed loading and design rules, both under the hypothesis of the undamaged and degraded structure. Therefore, the study examines the effects of increased traffic loads with the evolution of the code rules and, specifically, as defined by the Italian Technical Standards (NTC18), on a theoretically undamaged bridge. The results show a reduction in the safety factor across all critical structural components, apart from the lateral beams. These latter beams, in fact, benefit from a more comprehensive consideration of the overall resistance of the section, rather than just the localized stress values. Notably, the transition from the stress-based approach (Allowable Stresses Method, ASM) to a capacity-based evaluation of the full cross-section, as prescribed by NTC18, has minimal impact on elements subjected to purely axial loads, such as the hangers. Overall, the study aims to contribute to the understanding of the expected behaviour of an old structure facing the evolution of acting loads and allows the authors to restate, among other facts, the need to consider the expected degradation phenomena beyond the simple visual findings from surveys.

Keywords

Bowstring bridge / Reinforced concrete / Degradation / Original safety factor / Actual safety factor / Engineering / Civil Engineering

References

[1] Afsar DizajE, KashaniMM. Numerical investigation of the influence of cross-sectional shape and corrosion damage on failure mechanisms of rc bridge piers under earthquake loading. Bull Earthq Eng, 2020, 18104939-4961.

[2] A.N.A.S. (1952) Circolare n.820 (Italian Technical Circular), Ispettorato Tecnico, Apr 15, 1952

[3] Andrade C, Alonso C, Garcia D et al (1994) Remaining lifetime of reinforced concrete structures: effect of corrosion on the mechanical properties of the steel national association of corrosion engineers. 2nd Meeting, Life prediction of corrodible structures, Cambridge. NACE International, Houston, p 546–557

[4] AndradeC, AlonsoC, MolinaF. Cover cracking as a function of bar corrosion: Part I-experimental test. Mater Struct, 1993, 26: 453-464.

[5] ApostolopoulosCA, PapadakisV. Consequences of steel corrosion on the ductility properties of reinforcement bar. Constr Build Mater, 2008, 22122316-2324.

[6] Bertolini L, Bernhard E, Pietro Pet al (2013) Corrosion of steel in concrete: prevention, diagnosis, repair. John Wiley & Sons, Ltd., UK

[7] Buratti G, Cosentino A, Morelli F, et al (2019) Alcune considerazioni sull’evoluzione normativa dei carichi da traffico nella progettazione dei ponti stradali in italia. In: Proceedings of the XVIII Convegno L’ingegneria Sismica in Italia; ANIDIS, Ascoli Piceno, Italy. Pisa university press, IT, p 15–19

[8] Crank J (1979) The mathematics of diffusion. Oxford Science Publications, Clarendon Press, Oxford

[9] CuiF, ZhangH, GhosnM, et al. . Seismic fragility analysis of deteriorating rc bridge substructures subject to marine chloride-induced corrosion. Eng Struct, 2018, 155: 61-72.

[10] Di LorenzoG, FormisanoA, TerraccianoG, et al. . Iron alloys and structural steels from xix century until today: Evolution of mechanical properties and proposal of a rapid identification method. Constr Build Mater, 2021, 302: 124132.

[11] DuraCrete (1998) Modelling of degradation: DuraCrete–Probabilistic performance based durability design of concrete structures. EU-BriteEuRam III, Contract BRPR-CT95-0132, Project BE95-1347/R4-5

[12] EN 1990:2002/A1:2005 (2002) Eurocode: Basis of structural design, European Committee for Standardization (CEN), Brussels, BE

[13] EN 1992-1-1 (2004) Eurocode 2: Design of concrete structures-Part 1-1: General rules and rules for buildings, European Committee for Standardization (CEN), Brussels, BE

[14] Formisano A, Felitti M, Oliveto F, et al (2023) The robustness of reinforced concrete tied arch bridges: A case study. Struct Concr 24(4):4504–14

[15] Giudice EL, Di Marco G, Gallo M, et al (2018) The bridge over the river Cassibile: a structure in r/c bowstring scheme dating 1930, il ponte sul Cassibile. una struttura in ca tipo bowstring del 1930. Associazione AICAP, Italy. http://www.associazioneaicap.com

[16] GonzalezJ, AndradeC, AlonsoC, et al. . Comparison of rates of general corrosion and maximum pitting penetration on concrete embedded steel reinforcement. Cem Concr Res, 1995, 252257-264.

[17] HerreraD, TolentinoD. Fragility assessment of rc bridges exposed to seismic loads and corrosion over time. Materials, 2023, 1631100.

[18] HoD, LewisR. Carbonation of concrete and its prediction. Cem Concr Res, 1987, 173489-504.

[19] KumarR, BhattacharjeeB. Porosity, pore size distribution and in situ strength of concrete. Cem Concr Res, 2003, 331155-164.

[20] LuC, BuS, ZhengY, et al. . Deterioration of concrete mechanical properties and fracture of steel bars caused by alkali-silica reaction: A review. Structures, 2022, 35: 893-902.

[21] LupingT, GulikersJ. On the mathematics of time-dependent apparent chloride diffusion coefficient in concrete. Cem Concr Res, 2007, 374589-595.

[22] Ministero dei Lavori Pubblici (1996) D.M. del 09.01.1996, Norme tecniche per il calcolo, l’esecuzione ed il collaudo delle strutture in cemento armato normale e precompresso e per le strutture metalliche

[23] Ministero dei Lavori Pubblici - Consiglio Superiore (1957) Circolare del 23.05.1957, n.1472. Armatura delle strutture in cemento armato

[24] Ministero dei Lavori Pubblici - Presidenza del Consiglio Superiore - Servizio Tecnico Centrale (1965) Circolare del 17.05.1965, n.1547. Caratteristiche e modalità d’impiego del cemento armato degli acciai ad aderenza migliorata

[25] Min. LL.PP (1907) Decreto Ministeriale Jan 10, 1907: Prescrizioni normali per l’esecuzione delle opere in cemento armato (Italian Technical Code). G.U. Regno d'Italia n.28, Feb 02, 1907. https://www.legislazionetecnica.it/system/files/fonti/allegati/18-2/4527501/DMllpp10011907.pdf. Accessed 15  Jan 2025

[26] Min. LL.PP (1925) Circolare Jun 30, 1925. Nuovi sovraccarichi per il calcolo dei ponti in ferro (Italian Ministerial Circular)

[27] Min. LL.PP (1933) Regio Decreto Sep 15, 1933. Normale n.8: Carichi da considerare nel calcolo dei ponti per strade ordinarie (Italian Technical Code)

[28] Min. LL.PP (1945) Circolare n.6018 Jun 09, 1945 (Italian Ministerial Circular)

[29] Min. LL.PP (1946) Circolare n.772 Jun 12, 1946 (Italian Ministerial Circular)

[30] Min. LL.PP (1962) Circolare n.384 Feb 14, 1962: Norme relative ai carichi per il calcolo dei ponti stradali (Italian Ministerial Circular). https://www.legislazionetecnica.it/1082135/normativa-edilizia-appalti-professioni-tecniche-sicurezza-ambiente/circ-min-llpp-14-02-1962-n-384/ponti. Accessed 15 Jan 2025

[31] Min. LL.PP (1970) Circolare n.7091 Nov 04, 1970: Norme per la progettazione dei ponti stradali in acciaio (Italian Ministerial Circular)

[32] Min. LL.PP (1971) Legge n.1086, Nov 05, 1971. Norme per la disciplina delle opere in conglomerato cementizio, normale e precompresso ed a struttura metallica (Italian Technical Code). GU Repubblica Italiana n.321, Dec 21, 1971. https://www.gazzettaufficiale.it/eli/id/1971/12/21/071U1086/sg. Accessed 15 Jan 2025

[33] Min. LL.PP (1972) Decreto Ministeriale May 30, 1972: Norme tecniche alle quali devono uniformarsi le costruzioni in conglomerato cementizio, normale e precompresso ed a struttura metallica (Italian Technical Code). GU Repubblica Italiana n.190, Jul 22, 1972. https://www.legislazionetecnica.it/system/files/prd_allegati/_/13-9/1013508/1013507.pdf. Accessed 15 Jan 2025

[34] Min. LL.PP (1974) Decreto Ministeriale May 30, 1974: Norme tecniche per la esecuzione delle opere in cemento armato normale e precompresso e per le strutture metalliche (Italian Technical Code). GU Repubblica Italiana n.198, Jul 29, 1974. https://www.legislazionetecnica.it/1676826/normativa-edilizia-appalti-professioni-tecniche-sicurezza-ambiente/d-min-llpp-30-05-1974. Accessed 15 Jan 2025

[35] Min. LL.PP (1980a) Decreto Ministeriale Mar 26, 1980: Norme tecniche per la esecuzione delle opere in cemento armato normale e precompresso e per le strutture metalliche (Italian Technical Code). GU Repubblica Italiana n.176, Jun 28, 1980. https://www.legislazionetecnica.it/system/files/fonti/allegati/16-7/2923542/DMLLPP26031980-nt.pdf. Accessed 15 Jan 2025

[36] Min. LL.PP (1980b) Decreto Ministeriale Aug 02, 1980: Criteri generali e prescrizioni tecniche per la progettazione, esecuzione e collaudo dei ponti stradali (Italian Technical Code). GU Repubblica Italiana n.308, Nov 10, 1980. https://www.legislazionetecnica.it/system/files/fonti/allegati/19-3/5420070/DMLLPP-02-08-1980-ponti.pdf. Accessed 15 Jan 2025

[37] Min. LL.PP (1990) Decreto Ministeriale May 04, 1990, Aggiornamento alle norme tecniche per la progettazione, esecuzione e collaudo dei ponti stradali (Italian Technical Code). GU Repubblica Italiana n.24, Jan 29, 1991. https://www.gazzettaufficiale.it/eli/id/1991/01/29/090A2213/sg. Accessed 15 Jan 2025

[38] Min. LL.PP (1968) Circolare n.5226, Oct 15, 1968: Acciai ad aderenza migliorata per calcestruzzo armato (Italian Ministerial Circular). Presidenza del Consiglio Superiore, Servizio Tecnico Centrale

[39] Min. Infrastrutture e Trasporti (2005) Decreto Ministeriale Sep 14, 2005: Norme tecniche per le costruzioni (Italian Technical Code). GU Repubblica Italiana n.222, Sep 23, 2005. https://www.gazzettaufficiale.it/atto/serie_generale/caricaDettaglioAtto/originario?atto.dataPubblicazioneGazzetta=2005-09-23&atto.codiceRedazionale=05A08982&elenco30giorni=false. Accessed 15 Jan 2025

[40] Min. Infrastrutture e Trasporti (2008) Decreto Ministeriale Jan 14, 2008: Norme tecniche per le costruzioni (Italian Technical Code). GU Repubblica Italiana n.29, Feb 04, 2008. https://www.gazzettaufficiale.it/eli/id/2008/02/04/08A00368/sg. Accessed 15 Jan 2025

[41] Min. Infrastrutture e Trasporti (2018) Decreto Ministeriale Jan 17, 2018: Aggiornamento delle norme tecniche per le costruzioni (Italian Technical Code). GU Repubblica Italiana n.42, Feb 20, 2018. https://www.gazzettaufficiale.it/eli/id/2018/2/20/18A00716/sg. Accessed 15 Jan 2025

[42] Min. Infrastrutture e Trasporti (2022) Linee Guida per la classificazione e gestione del rischio, la valutazione della sicurezza ed il monitoraggio dei ponti esistenti (Italian Ministerial Guideline), Consiglio Superiore dei Lavori Pubblici. GU Repubblica Italiana n.196, Aug 23, 2022. https://cslp.mit.gov.it/circolari-e-linee-guida/linee-guida-la-classificazione-e-gestione-del-rischio-la-valutazione-della. Accessed 15 Jan 2025

[43] PapadakisVG, VayenasCG, FardisMN. Experimental investigation and mathematical modeling of the concrete carbonation problem. Chem Eng Sci, 1991, 465–61333-1338.

[44] Popovics S (1985a) Generalization of abrams’ law. ACI Mater J 82(2):136–146

[45] Popovics S (1985b) New formulas for the prediction of the effect of porosity on concrete strength. ACI J Proc 82(2):136–146. https://doi.org/10.14359/10321

[46] Regno d’Italia (1927) Regio Decreto, Legge n.1981, Sep 04, 1927: Nuove norme per l’accettazione degli agglomerati idraulici e l’esecuzione delle opere in conglomerato cementizio semplice ed armato (Italian Technical Code). GU Regno d’Italia n. 261, Nov 11, 1927. https://www.legislazionetecnica.it/9155618/normativa-edilizia-appalti-professioni-tecniche-sicurezza-ambiente/rdl-04-09-1927-n-1981/agglomerati-idraulici-e-opere-cemento-armato. Accessed 15 Jan 2025

[47] Regno d’Italia (1939) Regio Decreto, Legge n.2229, Nov 16, 1939: Norme per l’esecuzione delle opere in conglomerato cementizio semplice od armato (Italian Technical Code). GU Regno d’Italia n.92, Apr 18, 1940. https://www.legislazionetecnica.it/752598/normativa-edilizia-appalti-professioni-tecniche-sicurezza-ambiente/rd-16-11-1939-n-2229. Accessed 15 Jan 2025

[48] Roberge PR (2005) Corrosion engineering. Principles and Practice 1, Mc Graw Hill, New York, p 231–243

[49] RodriguezJ, OrtegaL, CasalJ. Load carrying capacity of concrete structures with corroded reinforcement. Constr Build Mater, 1997, 114239-248.

[50] Santarella L, Miozzi E (1948) Ponti Italiani in Cemento Armato. Ulrico Hoepli, Milano

[51] ShiX, XieN, FortuneK, et al. . Durability of steel reinforced concrete in chloride environments: An overview. Constr Build Mater, 2012, 30: 125-138.

[52] Soroka I (1979) Portland cement paste and concrete. Red Globe Press, London. https://doi.org/10.1007/978-1-349-03994-4

[53] Tuutti K (1982) Corrosion of steel in concrete. Doctoral Thesis (monograph), Division of Building Materials. Swedish Cement and Concrete Research Institute, Stockholm, SE

[54] UNI 3344 (1953) Systematic designation of steels: symbols related to the steel type, Italian National Unification Body (Italian Standard for Steel Materials)

[55] WinStrand 2024, EnExSys (2024) https://www.enexsys.com. Accessed 28 Nov 2024

Funding

Ministero dell’Università e della Ricerca(2022P7PF8J)

RIGHTS & PERMISSIONS

The Author(s)