Research needs towards a resilient community: Vulnerability reduction, infrastructural systems model, loss assessment, resilience-based design and emergency management

Most of the literature on resilience is devoted to its assessment. It seems time to move from analysis to design, to develop the tools needed to enhance resilience. Resilience enhancement, a close relative of the less fashionable risk mitigation, adds to the latter, at least in the general perception, a systemic dimension. Resilience is often paired with community, and the latter is a system. This chapter therefore discusses strategies to enhance resilience, endorses one of prevention rather than cure, and focuses in the remainder on the role played by systemic analysis, i.e. the analysis of the built environment modelled beyond a simple collection of physical assets, with due care to the associated interdependencies. Research needs are identified and include challenges in network modelling, the replacement of generic fragility curves for components, how to deal with evolving state of information

Ductility of wide-beam RC frames as lateral resisting system

[EN] Some Mediterranean seismic codes consider wide-beam reinforced concrete moment resisting frames (WBF) as horizontal load carrying systems that cannot guarantee high ductility performances. Conversely, Eurocode 8 allows High Ductility Class (DCH) design for such structural systems. Code prescriptions related to WBF are systematically investigated. In particular, lesson learnt for previous earthquakes, historical reasons, and experimental and numerical studies underpinning specific prescriptions on wide beams in worldwide seismic codes are discussed. Local and global ductility of WBF are then analytically investigated through (1) a parametric study on chord rotations of wide beams with respect to that of deep beams, and (2) a spectral-based comparison of WBF with conventional reinforced concrete moment resisting frames (i.e. with deep beams). Results show that the set of prescriptions given by modern seismic codes provides sufficient ductility to WBF designed in DCH. In fact, global capacity of WBF relies more on the lateral stiffness of the frames and on the overstrength of columns rather than on the local ductility of wide beams, which is systematically lower with respect to that of deep beams.Gómez-Martínez, F.; Alonso Durá, A.; De Luca, F.; Verderame, GM. (2016). Ductility of wide-beam RC frames as lateral resisting system. Bulletin of Earthquake Engineering. 14(6):1545-1569. doi:10.1007/s10518-016-9891-xS15451569146ACI (1989) Building code requirements for reinforced concrete (ACI 318-89). ACI Committee 318, American Concrete Institute, Farmington Hills, Michigan, USAACI (2008) Building code requirements for structural concrete (ACI 318-08) and commentary (318-08). ACI Committee 318, American Concrete Institute, Farmington Hills, Michigan, USAACI-ASCE (1991) Recommendations for design of beam-column connections in monolithic reinforced concrete structures (ACI 352R-91). Joint ACI-ASCE Committee 352, American Concrete Institute, Farmington Hills, Michigan, USAACI-ASCE (2002) Recommendations for design of beam-column connections in monolithic reinforced concrete structures (ACI 352R-02). Joint ACI-ASCE Committee 352, American Concrete Institute, Farmington Hills, Michigan, USAArslan MH, Korkmaz HH (2007) What is to be learned from damage and failure of reinforced concrete structures during recent earthquakes in Turkey? Eng Fail Anal 14(1):1–22ASCE (2007) Seismic Rehabilitation of Existing Buildings, ASCE/SEI 41-06. American Society of Civil Engineers, RestonASCE (2010) Minimum Design Loads for Building and Other Structures, ASCE/SEI 7-10. American Society of Civil Engineers, RestonBenavent-Climent A (2007) Seismic behavior of RC side beam-column connections under dynamic loading. J Earthquake Eng 11:493–511Benavent-Climent A, Zahran R (2010) An energy-based procedure for the assessment of seismic capacity of existing frames: application to RC wide beam systems in Spain. Soil Dyn Earthq Eng 30:354–367Benavent-Climent A, Cahís X, Zahran R (2009) Exterior wide beam-column connections in existing RC frames subjected to lateral earthquake loads. Eng Struct 31:1414–1424Benavent-Climent A, Cahís X, Vico JM (2010) Interior wide beam-column connections in existing RC frames subjected to lateral earthquake loading. Bull Earthq Eng 8:401–420BHRC (2004) Iranian Code of Practice for Seismic Resistant Design of Buildings. Standard Nº 2800, 3rd edn. Building and Housing Research Center, TehranBorzi B, Elnashai AS (2000) Refined force reduction factors for seismic design. Eng Struct 22:1244–1260Borzi B, Pinho R, Crowley H (2008) Simplified pushover-based vulnerability analysis for large-scale assessment of RC buildings. Eng Struct 30:804–820BSI (2004) Eurocode 2: Design of concrete structures: Part 1-1: General rules and rules for buildings. British Standards Institutions, LondonCalvi GM (1999) A displacement-based approach for vulnerability evaluation of classes of buildings. J Earthquake Eng 3(3):411–438CDSC (1994) Seismic construction code, NCSR-94. Committee for the Development of Seismic Codes, Spanish Ministry of Construction, Madrid, Spain (in Spanish)CDSC (2002) Seismic construction code, NCSE-02. Committee for the Development of Seismic Codes, Spanish Ministry of Construction, Madrid, Spain (in Spanish)CEN (2004) Eurocode 8: design of structures for earthquake resistance—part 1: general rules, seismic actions and rules for buildings. European Standard EN 1998-1:2003—Comité Européen de Normalisation, Brussels, BelgiumCEN (2005) Eurocode 8: design of structures for earthquake resistance—part 3: assessment and retrofitting of buildings. 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Earthquake Eng Struct Dynam 42(4):523–543De Luca F, Verderame GM, Gómez-Martínez F, Pérez-García A (2014) The structural role played by masonry infills on RC building performances after the 2011 Lorca, Spain, earthquake. Bull Earthq Eng 12(5):1999–2026Decanini LD, Mollaioli F (2000) Analisi di vulnerabilità sismica di edifici in cemento armato pre-normativa. In: Cosenza E (ed) Comportamento sismico di edifici in cemento armato progettati per carichi verticali. CNR—Gruppo Nazionale per la Difesa dei Terremoti, Rome (in Italian)Dolšek M, Fajfar P (2004) IN2—a simple alternative for IDA. In: Proceedings of the 13th World conference on Earthquake Engineering. August 1–6, Vancouver, Canada. Paper 3353Domínguez D, López-Almansa F, Benavent-Climent A (2014) Comportamiento para el terremoto de Lorca de 11-05-2011, de edificios de vigas planas proyectados sin tener en cuenta la acción sísmica. Informes de la Construcción 66(533):e008 (in Spanish)Domínguez D, López-Almansa F, Benavent-Climent A (2016) Would RC wide-beam buildings in Spain have survived Lorca earthquake (11-05-2011)? Eng Struct 108:134–154Dönmez C (2013) Seismic Performance of Wide-Beam Infill-Joist Block RC Frames in Turkey. J Perform Constr Facil 29(1):04014026Fadwa I, Ali TA, Nazih E, Sara M (2014) Reinforced concrete wide and conventional beam-column connections subjected to lateral load. Eng Struct 76:34–48Fardis MN (2009) Seismic design, assessment and retrofitting of concrete, Buildings edn. Springer, LondonGentry TR, Wight JK (1992) Reinforced concrete wide beam-column connections under earthquake-type loading. Report no. UMCEE 92-12. Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USAGómez-Martínez F (2015) FAST simplified vulnerability approach for seismic assessment of infilled RC MRF buildings and its application to the 2011 Lorca (Spain) earthquake. Ph.D. Thesis, Polytechnic University of Valencia, SpainGómez-Martínez F, Pérez García A, De Luca F, Verderame GM (2015a) Comportamiento de los edificios de HA con tabiquería durante el sismo de Lorca de 2011: aplicación del método FAST. Informes de la Construcción 67(537):e065 (in Spanish)Gómez-Martínez F, Pérez-García A, Alonso Durá A, Martínez Boquera A, Verderame GM (2015b) Eficacia de la norma NCSE-02 a la luz de los daños e intervenciones tras el sismo de Lorca de 2011. In: Proceedings of Congreso Internacional sobre Intervención en Obras Arquitectónicas tras Sismo: L’Aquila (2009), Lorca (2011) y Emilia Romagna (2012), May 13–14, Murcia, Spain (in Spanish)Gómez-Martínez F, Verderame GM, De Luca F, Pérez-García A, Alonso-Durá, A (2015c). High ductility seismic performances of wide-beam RC frames. In; XVI Convegno ANIDIS. September 13–17, L'Aquila, ItalyHawkins NM, Mitchell D (1979) Progressive collapse of flat plate structures. 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Concrete Columns Confined with Large Rupture Strain Composites: An Emerging Field

2020, Springer Nature Singapore Pte Ltd. Large rupture strain (LRS) fibre-reinforced polymer (FRP) composites are emerging as a competitive solution for the seismic retrofitting of reinforced concrete (RC) columns. Research on the confinement of concrete with FRP to date has primarily been focused on traditional FRP composites exhibiting ultimate tensile strains generally less than 3%. Such composites are usually made from carbon, glass or aramid fibres. For this reason, existing knowledge of FRP confinement needs to be assessed with the use of LRS FRP composites that possess tensile strain capacities well in excess of traditional FRP materials. Initially, this paper introduces large rupture strain fibres. Then, a summary of existing research on the compressive behavior of LRS FRP-confined concrete columns is provided. The general form of the compressive stress-strain relationship of such confined concrete is bilinear and similar to that of circular columns confined with traditional FRP composites. However, similar to square and rectangular columns insufficiently confined with traditional FRPs, square and rectangular LRS FRP-confined columns exhibit a strength softening region before the FRP activates. It is expected that if the stiffness of LRS FRP confinement materials is increased, then a more traditional bilinear behavior could be exhibited. Finally, recommendations for future research are provided

Incremental seismic rehabilitation of RC buildings: An application to the school buildings of Basilicata region (Southern Italy)

During the last decade, comprehensive assessment programs have been carried out in Italy especially on public and strategic structures like hospitals and schools. Most of these seismic vulnerability assess-ments for non-seismically designed existing school buildings were carried out in the aftermath of the 2002 Molise earthquake, in compliance with the Or-dinances of the Italian Prime Minister (OPCM) 3274/2003 and 3362/2004. The main purpose of these assessments was the construction of priority lists in order to effectively set up strengthening intervention programs. The huge amount of resources needed to retrofit all vulnerable structures requires accurate studies for setting up strategies able to reduce the seismic risk to allowable levels optimizing the use of the available resources. To this end, the choice of seismic upgrading instead of full retrofit appears to be advisable and even mandatory, the former being less expensive and time-consuming thus allowing to obtain a more diffuse and rapid improvement of the seismic safety. With this aim, the assessment results on a non-seismically designed school building located in Basilicata region (Southern Italy) has been analysed in order to find out whether or not an Incremental Seismic Rehabilitation strategy could be effectively applicable. An application of the proposed procedure has been made on a case study school building with RC structure designed only to gravity loads. The structure has been firstly evaluated through non linear static analysis and, based on its performance and, specifically, on the sequence and type of local failures, a design for a staged seismic rehabilitation has been prepared. The design critical choices adopting an incremental seismic re-habilitation, quite different from a single-staged re-habilitation usually adopted by professional engineers, have been identified and discussed

A Simplified Numerical Method for Blast Induced Structural Response Analysis

Efficiently and accurately predicting structural dynamic response and damage to external blast loading is a big challenge to both structural engineers and researchers. The conventional numerical treatment to this problem is proved being able to give reliable predictions, however at the cost of enormous computational time and resource. Simplified SDOF approach is popularly used in design as it is straightforward to use and also gives good structural response predictions if the response is governed by a global response mode (shear or bending) and the accurate dynamic deflection curve is available, but it cannot predict the detailed local structural damage. In this study, a new numerical approach that combines the recently proposed two-step method and the static condensation method is proposed to analyze structure response and collapse to blast loads. The two-step method divides the structural response into two phases, i.e. forced vibration phase (blastloading duration) and free vibration phase. Single- Degree-of-Freedom system approach is adopted to solve the structural element responses at the end of the forced vibration phase, and the structural free vibration simulation is carried out using the hydro-code LS-DYNA to calculate the detailed structural response and damage. The static condensation technique is utilized to condense structural components that are relatively away from the explosion center to further reduce the computational effort. To demonstrate the proposed method, the structural responses of a three story RC frame to blast loads are calculated by four approaches, i.e. the traditional detailed FE simulation, the two-step method, the model condensation method, and the new combined two-step and dynamic condensation method. Through the results comparison, the efficiency and accuracy of the proposed combined approach are demonstrated