Eurocode 8 is undergoing a revision process encompassing novel ductility classes, damage limitation limits, local ductility conditions corresponding to detailing prescriptions and structural irregularity criteria. In this paper, we specifically assessed the influence of an irregularity in elevation, imposed by different elevations, on the first and third storeys of buildings, and variations in the cross-sections of columns during the seismic response of reinforced concrete (RC) structures. To assess this impact, an extensive examination was conducted on thirteen five-storey moment-resisting frame (MRF) buildings. The design of those structures was carried out on the Robot Structural Analysis Professional framework following the current generation of Eurocodes 2 and 8, and the seismic response analysis was carried out using the SeismoStruct v2024 software. The results were compared to evaluate the influence of imposed irregularities in elevation due to the increasing height, column cross-section, mass, and resistance variation. The study’s outcomes revealed that, for DCM structures, the imposed irregularities in elevation have different impacts on the seismic response. Increasing the heights of ground or middle floor have substantial deleterious effects on the building’s seismic response. The planned geometry and variations in the cross-sections of columns substantially impact inter-storey drift and base shear. The effects of mass and resistance irregularities were neglected in this study. As such, more studies on those matters are necessary to allow our results to be further generalised.

The recent seismic activity highlights the crucial need to enhance seismic design and safety assessment methods, particularly for irregular structures, in both new and existing constructions. The present study focuses on structural irregularities in elevation for buildings, as the design of structural systems involves multiple variables that often result in irregularities in many buildings. This work aims to perform a comparative assessment of the criteria adopted for the evaluation of the structural irregularities in elevation present in European and international seismic codes. This paper is structured as follows: Firtsly, it discusses structural irregularities and more specifically the most common types of structural damage due to seismic events. Then, it shows the documented experiences of structural damages in seismic events associated with structural irregularities in China, Italy, Spain, Nepal and Mexico. Additionaly, it discusses the requirements of the standards on irregularities and their limitation in that matter. At the end of this section, the different approaches of each code in irregularities in elevation are compared. All assessed seismic codes addresses the structural irregularity issue, attributing the desired characteristics of a seismic-resistant structure. However, there are considerable development differences between norms, demonstrated on ambiguity of few codes on criteria of vertical irregularies.

Resumo Este trabalho tem como objetivo avaliar tecnicamente a reciclagem de resíduos de construção civil provenientes de concreto e argamassa gerados em canteiro de obras de construtora de grande porte. Foram analisados traços de contrapiso e de emboço interno e externo, considerando substituição de areia natural por agregado reciclado nos percentuais de 25% e 50%. Foram avaliadas propriedades no estado fresco (consistência, teor de ar incorporado, densidade de massa), no estado endurecido (densidade de massa aparente, módulo de elasticidade dinâmico, resistência à tração na flexão, resistência à compressão) e na argamassa de revestimento (aderência, fissuras e permeabilidade à água). Verificou-se que o teor de material pulverulento dos agregados reciclados foi menor do que 10%, não havendo potencial impacto na fissuração. Observou-se também elevação do teor de ar incorporado com elevação do teor de substituição do agregado natural pelo reciclado nos traços de contrapiso e de emboço externo. Já para o emboço interno o comportamento foi o oposto. Em relação à aderência à tração, não houve impacto com relação ao teor de substituição. Para resistência à compressão e à tração na flexão, houve variações significativas, porém todas as argamassas permanecem no mesmo extrato de classificação segundo a NBR 13281. No que compete às fissuras, foram reduzidas com a substituição de areia natural por agregado reciclado. Em se tratando de permeabilidade à água, os resultados encontrados foram considerados baixos para todos os tipos de argamassas.

The structural vulnerability of RC structures during major seismic events raises several concerns regarding structural design and behaviour. Additionally, corrosion’s impact on steel and concrete, including a reduction in ductility, confinement and strength, can compromise structural performance, especially for reversal loading. This work investigates the combined effect of corrosion and seismic actions on the structural performance of RC structures. Numerical models of RC structures with 0%, 5%, 10%, 15% and 20% corrosion were proposed. The effect of corrosion in the numerical models was calibrated based on experimental studies carried out on corroded RC elements. Afterwards, we considered the scenario of corrosion in all peripheral structural elements of 5- and 10-storey MRF structures in three distinct conditions. To enforce vertical irregularity, we have imposed vertical irregularity at the ground level in each structure. An adaptive pushover analysis was performed to assess the effect of corrosion and vertical irregularity on the seismic response. The results demonstrate that, for the levels of 5% and 10% corrosion, uniform corrosion produces a deleterious impact on structural responses in 10- and 5-storey MRF structures, respectively, regardless of the level of irregularity of the elevation. However, the irregularity generates a higher impact in the seismic response than the uniformly distributed corrosion in height. The combined effect of those parameters must be considered in seismic codes for new and existing buildings in order to maintain safe performance levels.