Seismic Loss Estimation in Pre-1970 Residential RC Buildings: The Role of Infills and Services in Low–Mid-Rise Case Studies

Gaudio, Carlo Del; Risi, Maria Teresa De; Scala, Santa Anna; Verderame, Gerardo Mario

doi:10.3389/fbuil.2020.589230

Cited by 4 publications

(3 citation statements)

References 46 publications

(61 reference statements)

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“…Rectangular columns are always oriented in the longitudinal direction. Further details can be found in [26].…”

Section: Morra De Sanctis (Gld)mentioning

confidence: 99%

Seismic Performance Assessment of as-Built and Retrofitted Rc Buildings Considering the Influence of Infills: Pre-‘70 Low-Mide Rise Case-Studies

Risi¹,

Scala²,

Gaudio³

et al. 2021

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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The seismic assessment and retrofit of non-conforming Reinforced Concrete (RC) buildings still represent a challenge for researchers and practitioners worldwide due to several aspects. On one hand, low standards RC buildings typically present some failure typologies very different from newly designed buildings, and such failure modes should be properly modelled for a reliable seismic performance assessment. On the other hand, retrofitting strategies should be chosen carefully looking both at safety at collapse and at seismic capacity at less severe performance levels, considering nonstructural components as well. Masonry infills, typically defined as non-structural components despite their structural role, significantly affect the seismic behavior of existing RC buildings, especially at low-medium intensity measures. Therefore, when the seismic performance of as-built or retrofitted RC buildings is assessed, their contribution should be considered. In this work, a preliminary analysis of two 4-storey low-standard RC buildings, different for design typology, is presented, based on static nonlinear analyses. First, case-study buildings, representative of Italian pre-70 residential buildings, have been assessed in their "bare" configuration (without infills), as common in design practice, in a code-based approach (according to Italian code). Based on the asbuilt assessment outcomes, their retrofit has been designed by means of two main strategies: (1) the complete resolution of all the shear failures (in columns or joints), if any; (2) the reduction of the displacement demand by means of RC column jacketing, when necessary, along with the resolution of shear failures (as for the previous strategy). Then, both the as-built and retrofitted building configurations have been modelled and analysed explicitly considering the presence of infills and shear-critical elements. Fragility curves have been obtained at different Damage States according to European Macroseismic Scale EMS-98, considering record-to-record variability, and compared to each other. Remarks about the choice among strengthening strategies are carried out, based on these outcomes and on a preliminary estimation of the expected mean annual losses for the investigated buildings.

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“…Rectangular columns are always oriented in the longitudinal direction. Further details can be found in [26].…”

Section: Morra De Sanctis (Gld)mentioning

confidence: 99%

Seismic Performance Assessment of as-Built and Retrofitted Rc Buildings Considering the Influence of Infills: Pre-‘70 Low-Mide Rise Case-Studies

Risi¹,

Scala²,

Gaudio³

et al. 2021

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

Self Cite

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show abstract

“…Recent earthquakes have highlighted the importance of assessing the seismic vulnerability of the infilled RC structures considering the walls' impact [2,3]. Their interaction with the RC elements and their poor seismic behavior (both in-plane and out-of-plane) was the cause of a significant portion of the casualties, structural damages, and collapses and economic losses [4].…”

Section: Introduction 1motivation and Literature Reviewmentioning

confidence: 99%

Effect of the Openings on the Seismic Response of an Infilled Reinforced Concrete Structure

2022

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The seismic behavior of the infill masonry infill walls has a significant impact on the global response of reinforced concrete frame structures. One factor influencing its behavior is the existence of openings in the walls, such as doors and windows, which are crucial for the infill seismic performance. Although the numerical simulation of the seismic behavior of RC buildings with infill walls has evolved significantly in recent years in terms of micro- and macro-modelling, most of the existing studies are only related to infill walls without openings. Based on this motivation, four main objectives were defined for this research work: (i) present a simplified modeling approach and its calibration to simulate the seismic behavior of infill walls with central openings such as windows; (ii) evaluate the impact of the openings on the global seismic response of an RC building; (iii) study the impact of the irregular distribution of the infill walls (vertical and in-plane) on the global seismic response of an RC building; and (iv) study the impact of the central openings ratio (i.e., relative percentage between opening and infill wall area) on the global seismic response of an RC building structure. A four-story infilled RC building was used as a case study to perform parametric analyses investigating the impact of the masonry infill walls’ irregular distribution (vertical and in-plan) and their openings ratio. The results are discussed in terms of natural frequencies and vibration modes, initial lateral stiffness, and maximum lateral resistance. This study found that the openings caused a reduction in the natural frequencies of about 20% compared with the full infill (without openings). The openings did not modify the vibration modes. In addition, the openings reduced the initial stiffness by about 20% compared with the model without openings. The maximum strength increased about 50% with the infill walls, but this was reduced by the openings by 20%.

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“…Most of these structures were built before the enforcement of modern seismic codes. Moreover, the seismic response of some nonstructural elements is directly responsible for damages, collapses, casualties, and economic losses, and the impact on post-earthquake rehabilitation costs [11] is estimated to be about 50% of the total repair costs [12]. Around 40% of EU buildings are located in seismic regions and designed with substandard safety requirements, of which 65% of them need both energy and seismic retrofitting.…”

Section: Introductionmentioning

confidence: 99%

Interactions between Seismic Safety and Energy Efficiency for Masonry Infill Walls: A Shift of the Paradigm

et al. 2022

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Currently, the upgrade of existing reinforced concrete (RC) buildings focuses only on energy retrofitting measures due to the current policies promoted in the scope of the European Green Deal. However, the structural deficiencies are not eliminated, leaving the building seriously unsafe despite the investment, particularly in seismic-prone regions. Moreover, the envelopes of existing RC buildings are responsible for their energy efficiency and seismic performance, but these two performance indicators are not usually correlated. They are frequently analyzed independently from each other. Based on this motivation, this research aimed to perform a holistic performance assessment of five different types of masonry infill walls (i.e., two non-strengthened walls, two walls with seismic strengthening, and one wall with energy strengthening). This performance assessment was performed in a three-step procedure: (i) energy performance assessment by analyzing the heat transfer coefficient of each wall type; (ii) seismic performance assessment by analyzing the out-of-plane seismic vulnerability; (iii) cost–benefit performance assessment. Therefore, a global analysis was performed, in which the different performance indicators (structural and energy) were evaluated. In addition, a state-of-the-art review regarding strengthening techniques (independent structural strengthening, independent energy strengthening, and combined structural plus energy strengthening) is provided. From this study, it was observed that the use of the external thermal insulation composite system reduced the heat transfer coefficient by about 77%. However, it reduced the wall strength capacity by about 9%. On the other hand, the use of textile-reinforced mortar improved the strength and deformation capacity by about 50% and 236%, but it did not sufficiently reduce the heat transfer coefficient. There is a need to combine both techniques to simultaneously improve the energy and structural energy performance parameters.

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Seismic Loss Estimation in Pre-1970 Residential RC Buildings: The Role of Infills and Services in Low–Mid-Rise Case Studies

Cited by 4 publications

References 46 publications

Seismic Performance Assessment of as-Built and Retrofitted Rc Buildings Considering the Influence of Infills: Pre-‘70 Low-Mide Rise Case-Studies

Seismic Performance Assessment of as-Built and Retrofitted Rc Buildings Considering the Influence of Infills: Pre-‘70 Low-Mide Rise Case-Studies

Effect of the Openings on the Seismic Response of an Infilled Reinforced Concrete Structure

Interactions between Seismic Safety and Energy Efficiency for Masonry Infill Walls: A Shift of the Paradigm

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