A comparative study of seismic diaphragm design forces for RC dual system buildings

Correal, Juan F.; Hidalgo, Víctor; Reyes, Juan C.; Ángel, Christiam C.

doi:10.1007/s10518-020-00870-8

Cited by 3 publications

(1 citation statement)

References 26 publications

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“…Without any prior experience to draw from, NYC quickly became the most severely affected city and the US epicenter for the pandemic during the early spring 2020 2,5,18,19 . Elmhurst Hospital, one of the five trauma centers included in our study, was frequently noted to be one of the worst affected hospitals in the country and was called the “epicenter of the epicenter” by the media 20 . The Bronx, where two of our trauma centers are located, had the highest hospitalizations and fatalities due to COVID-19 per 100,000 population in the city and, at that time, in the world 21 .…”

Section: Discussionmentioning

confidence: 99%

When New York City was the COVID-19 pandemic epicenter: The impact on trauma care

Liveris

Stone

Markel

et al. 2021

J Trauma Acute Care Surg

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BACKGROUND:During early spring 2020, New York City (NYC) rapidly became the first US epicenter of the COVID-19 pandemic. With an unparalleled strain on health care resources, we sought to investigate the impact of the pandemic on trauma visits and mortality in the United States' largest municipal hospital system. METHODS:We conducted a retrospective multicenter cohort study of the five level 1 trauma centers in NYC's public health care system, New York City's Health and Hospitals Corporation. Clinical characteristics, mechanism of injury, and mortality of trauma patients presenting during the early pandemic (March 1, 2020, to May 31, 2020) were compared with a similar period in the previous 2 years.To account for important patient and hospital-level confounding variables, we created a propensity score for treatment and applied inverse probability weighting. RESULTS:In March to May 2020, there was a 25% decrease in median number of monthly trauma visits (693 vs. 528; p = 0.02) but a 50% increase (15% vs. 22%; p = <0.001) in patients presenting for penetrating injuries, compared with the same period for 2018 and 2019. Injured patients with COVID were significantly more likely to die compared with those without COVID-19 (10.5% vs. 3.6%; p < 0.001). Overall, there was no significant difference in mortality for non-COVID-injured New Yorkers cared for in 2020 compared with 2018 and 2019. Less severely injured non-COVID patients (Injury Severity Score, <15), however, were significantly more likely to die compared with this same subgroup in 2018 and 2019 (adjusted relative risk, 2.7 [95% confidence interval, 1.5-4.7]). CONCLUSION:Despite a decline in overall trauma visits during the early part of the COVID pandemic in NYC, there was a significant increase in the proportion of penetrating mechanisms. Less-injured non-COVID patients experienced an increase in mortality in the early pandemic, possibly from a depletion of human and hospital resources from the large influx of COVID patients. These data lend support to the safeguarding of trauma system resources in the event of a future pandemic. (

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Section: Discussionmentioning

confidence: 99%

When New York City was the COVID-19 pandemic epicenter: The impact on trauma care

Liveris

Stone

Markel

et al. 2021

J Trauma Acute Care Surg

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In-plane capacity of existing post-WWII beam-and-clay block floor systems

Marini

Belleri

Passoni

et al. 2022

Bull Earthquake Eng

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A growing attention has been paid to the deep renovation of RC buildings, particularly focusing on their structural vulnerability and on the development of retrofit strategies; however, the issue of the in-plane diaphragm action and the capacity of existing floors has rarely been addressed. Although floor capacity does not seem critical for the seismic capacity of existing structures, commonly affected by greater vulnerabilities, it may become critical when an additional lateral force resisting system is introduced. This paper investigates the in-plane capacity of beam and hollow-clay-block floor system, typical of the European post-WWII RC buildings. Considering the diaphragm action as associated with an in-plane tied-arch mechanism developing within the floor thickness, the main failure mechanisms are discussed, and some simplified equations are provided to preliminary estimate the maximum capacity of floors. Experimental and numerical analyses are than carried out to validate the simplified analytical model. The relevant influence of possible staircase openings on the in-plane load paths and on diaphragm flexibility and capacity are also considered. Finally, the influence of the floor capacity on the seismic vulnerability assessment and in the conceptual design of a seismic retrofit intervention is discussed. This preliminary study shows that only some of the beam-and-block floor systems have a reliable in-plane capacity, while other typologies cannot serve as floor diaphragms. When the diaphragm action can be relied upon, the diaphragms often exhibit a fairly stiff behaviour up to a brittle failure, which is commonly associated with the ultimate capacity at the tied-arch supports.

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Shaking Table Tests of a Novel Flat Slab-Flanged Wall (FSFW) Coupled System with Embedded Concrete-Filled-Steel-Tubes in Wall Piers

et al. 2022

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The flat slab-flanged wall (FSFW) coupled system has gained popularity in recent years; however, its seismic performance remains an issue, as beams and columns in it are commonly eliminated. To tackle this problem, embedding concrete-filled steel tubes (CFSTs) in wall piers has been proposed to strengthen the system; the viability of this approach has been verified at the member level. Along this line, this study embarks on a shaking table testing of a 1/8-scale five-story FSFW structure equipped with CFSTs in walls, with an aim to understand the overall seismic behavior of such an enhanced system. As with the practice in many countries, the plan layout of the test structure consisted of four rows of wall piers, thus presenting a ‘fish-bone’ floor configuration that relied only upon the walls to resist gravity and lateral loads. The structure was subjected to a suite of input ground motions along with white-noise excitations. By so doing, its damage progression, pattern and dynamic characteristics were clearly identified. Furthermore, a non-linear time history analysis was conducted using PERFORM-3D, and the goodness-of-fit of the computed responses to the experimental records was examined. Findings indicated that the application of CFSTs was instrumental in resisting the simulated earthquake loads acting on the FSFW system, hence the global response limits required by codes of practice were met, even in the case of extremely strong earthquakes. Nevertheless, the junction between the shear walls and floor slabs was found to be the weakest links in the whole system. Designers are thus cautioned to implement proper detailing in those regions to prevent local distress, though it did not appear to acutely impair the system’s collapse-resisting capacity.

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A comparative study of seismic diaphragm design forces for RC dual system buildings

Cited by 3 publications

References 26 publications

When New York City was the COVID-19 pandemic epicenter: The impact on trauma care

When New York City was the COVID-19 pandemic epicenter: The impact on trauma care

In-plane capacity of existing post-WWII beam-and-clay block floor systems

Shaking Table Tests of a Novel Flat Slab-Flanged Wall (FSFW) Coupled System with Embedded Concrete-Filled-Steel-Tubes in Wall Piers

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