Association of epicardial and visceral adipose tissue in relation to subclinical cardiac dysfunction in Chinese: Danyang study.

OBJECTIVE: Our study aims to examine the associations of visceral adipose tissue (VAT) and epicardial adipose tissue (EAT) with subclinical cardiac dysfunction in a Chinese population. DESIGN: Cross-sectional. BACKGROUND: EAT and VAT are the most important ectopic fat pools which were previously shown to be associated with subclinical cardiac dysfunction. However, few studies simultaneously measured both EAT thickness and VAT area, and explored their associations with cardiac dysfunction. Our study aims to examine the associations of VAT and EAT with subclinical cardiac dysfunction in a Chinese population. METHODS: The study subjects were recruited from Danyang County from 2018 to 2019. Using Philips CX50, we recorded EAT thickness at the end-systole in a long-axis view. The subclinical systolic and diastolic function were assessed by two-dimensional speckle tracking, and transmitral and tissue Doppler imaging, respectively. Using Omron HDS-2000, we measured VAT area by dual bioelectrical impedance analysis. RESULTS: The 1558 participants (age, 52.3±12.8 years) included 930 (59.7%) women. Compared with women, men had higher VAT area (99.4 vs 70.1 cm2; p<0.0001) but lower EAT thickness (4.02 vs 4.46 mm; p<0.0001). In simple correlation analyses, EAT thickness and VAT area were positively associated with E/e' ratio (r=0.16 to 0.20; all p<0.0001) and negatively with global longitudinal strain (GLS) and e' (r=-0.12 to -0.37; all p<0.0001). Furthermore, VAT area was associated with left ventricular ejection fraction (LVEF) (r=-0.14; p<0.0001). After adjustment for confounding factors, the association of EAT with GLS and that of VAT with e' and E/e' ratio remained significant (all p≤0.001), whereas the associations of EAT with subclinical diastolic dysfunction and that of VAT with systolic function became non-significant (all p≥0.11). Analyses on further adjustment for LVEF showed similar results. CONCLUSIONS: Increased EAT thickness was associated with worse subclinical systolic dysfunction, while greater VAT area was associated with early diastolic dysfunction.

Flexural Behavior of Damaged Hollow RC Box Girders Repaired with Prestressed CFRP.

In recent years, numerous studies have explored the benefits of utilizing prestressed carbon fiber-reinforced polymer (CFRP) for strengthening concrete structures. However, research on the reinforcement of prestressed CFRP on full-scale hollow RC box girders, particularly damaged bridges, remains limited. In this study, both experiments and finite element analysis (FEA) were performed to investigate the flexural behavior of full-scale hollow RC box girders with varying degrees of damage, which were strengthened using CFRP with different levels of prestress. The adhesive behavior of the CFRP-concrete interface was considered in the FEA. Numerical simulations were conducted to assess the flexural behaviors of the girders, including failure modes, yield and ultimate loads, and deflections. The results revealed that the application of prestressed CFRP efficiently increased the yield and ultimate loads of the box girders. Specifically, when the degree of damage of the hollow box girder was less than 23%, the flexural bearing capacity of the repaired girder could be recovered after being strengthened with two prestressed CFRP strips measuring 50 mm in width and 3 mm in thickness. However, the risk of premature debonding at the CFRP-concrete interface increased when the prestressing level of CFRP and degree of damage of hollow RC box girders exceeded 35% and 40%, respectively. These findings suggest that the use of prestressed CFRP may be a promising method for repairing damaged hollow RC box girders, but careful consideration of the degree of damage and prestressing level would be necessary to ensure the effectiveness and safety of the repair.

Flexural Behavior of Full-Scale Damaged Hollow RC Beams Strengthened with Prestressed SCFRP Plate under Four-Point Bending.

The advantages of using prestressed carbon fiber reinforced polymer (CFRP) for strengthening and retrofitting structures have been reported in recent years. In this regard, most of the studies on prestressed CFRP technique have been carried out in the laboratory test with small-scale and no damage (reinforced concrete) RC beam. However, the real structures that need to be retrofitted in service are often degraded or damaged due to early cracking. This paper aims at studying the effect of prestressed CFRP method on full-scale and damaged RC beams. The damaged levels of four full-scale damaged hollow RC beams taken from an old bridge were evaluated. One damaged beam was tested to check the residual capacity, and the other three were strengthened with prestressed composite strengthened CFRP and steel-carbon fiber reinforced polymer (SCFRP). The flexural behavior of non-strengthened and prestressed strengthened beams was investigated. During the experiments, the failure modes, deflection, yield and ultimate load, strains of concrete, steel reinforcements, and SCFRP were measured and analyzed. The results showed that the stiffness at the elastic stage was increased by 64.9%, 66.9%, and 67.1% after strengthened by SCFRP with 30%, 40%, and 60% prestressing level. Moreover, the ultimate load of damaged hollow RC beams were improved by 19.53%, 21.82%, and 31.9%, respectively. The flexural behavior of the severely damaged RC beam with strength reduction coefficient of 0.65 can be recovered after being strengthened by SCFRP with 40% prestressing levels. Meanwhile, SCFRP-concrete interface debonding failure occurred when the prestressing level exceed 60%, and the characteristics of brittle failure became more evident with increased prestressing level of the SCFRP.