Search

ACI 318-19 and ASCE 7-22 specify code-compliant and emulative seismic force-resisting systems (SFRS) including intermediate precast shear wall systems. For the seismic design of a precast shear wall system, its successful performance heavily depends on the capacity design of inevitable discrete connections between precast wall panels, thus playing a critical role in controlling yielding to occur within steel reinforcements at the vicinity of intended locations or components. This is imperative for achieving not only ductility but also adequate energy dissipation, ensuring the system can effectively withstand seismic forces. To this end, the overstrength is essentially required to prevent any brittle failure, and the connections designed not to yield can be protected by addressing the 1.5Sy condition as specified in ACI 318-19 and ASCE 7-22. However, there can be a blind spot for the precast connections designed to yield. To this end, this study showed some cases based on practical examples from which a reasonable magnitude of overstrength (Sy) was tentatively recommended for better safety in the seismic design of the intermediate precast shear wall system with precast connections designed to be yielded. [ABSTRACT FROM AUTHOR]

Precast prestressed hollow core slabs (PPHCSs) are widely used in the construction of multistory cross-wall structures, but the floors are vulnerable to progressive collapse induced by unexpected loadings due to weak links between PPHCSs. Despite this fact, limited studies have been carried out on the progressive collapse resistance of PPHCSs. In this study, quasi-static tests were conducted to evaluate the progressive collapse resistance of PPHCSs. The test parameters were the types of connectors [i.e., single rebar connector (S1), double rebar connector (S2), partially debonded rebar connector (S3), kinked rebar connector (S4), and partial hinge rebar connector (S5)]. The progressive collapse resistance including the load-carrying capacity, deformation capacity, failure modes, and main load-resisting mechanism was evaluated. The energy dissipation capacity of all specimens was estimated based on the energy balance principle, and the energy dissipation capacity of S5 was 91%, 303%, 190%, and 85% greater than that of S1–S4, respectively. Further, the pseudo-static response of each specimen was calculated using a simplified dynamic assessment method. The test results revealed that all specimens generated effective compressive arch action and catenary action, and the ultimate strength (72.56 kN) of S5 using partial hinge was 64%, 334%, 110%, and 45% greater than that of S1–S4, respectively. [ABSTRACT FROM AUTHOR]

Introduction: Cryptosporidium , Cystoisospora , and Giardia duodenalis are gastrointestinal protozoa parasites that cause diarrhea in various animals. However, information regarding the detection and phylogenetic characterization of gastrointestinal protozoa parasites in cats is limited throughout South Korea. Therefore, this study aimed to determine the detection and identify subspecies of gastrointestinal protozoa parasites in cats from South Korea., Methods: A total of 290 fecal samples were collected from stray, companion, and shelter cats in six provinces. Cryptosporidium , Cystoisospora , and G. duodenalis were identified by PCR. All positive samples were subtyped by PCR and sequencing of gp60 , ITS-1 , tpi , bg , and gdh ., Results: The overall detection of gastrointestinal protozoan parasitic infection was 17.93%. G. duodenalis was the most prevalent, with 7.93%, followed by Cystoisospora spp. (7.24%) and Cryptosporidium spp. (4.48%). In addition, C. felis (n=10), C. parvum (n=2), C. ryanae (n=1), Cystoisospora felis (n=14), Cystoisospora suis (n=5), Cystoisospora ohioensis (n=1), Cystoisospora spp. were identified in subspecies analysis of positive samples. C. felis showed a significant association with diarrhea (7.81%) and living condition (6.04%), and Cystoisospora felis in diarreha (9.38%) according to detection. Through phylogenetic analysis of the tpi, bg, and gdh genes from 23 G. duodenalispositive samples, it was confirmed that the samples of present study belonged to assemblage A, B, C, and D., Discussion: South Korean cats have a high rate of gastrointestinal protozoan parasites infection with cat-specific Cryptosporidium and Cystoisospora, which are associated with living conditions and diarrhea symptoms. Moreover, zoonotic and other animal-specific subtype of protozoan parasites have been detected in cat feces., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Yun, Moon, Lee, Kang, Ku and Hwang.)