Search

Beam–column joints are critical in reinforced concrete moment-resisting frames. Adequately designed beam–column joints support the plastic hinging of the adjoining beams under seismic actions and transfer gravity loads, both of which are critical for the energy dissipation and survival of buildings during earthquakes. Beam–column joints in exterior frames of buildings are occasionally eccentric such that the axes of the beam and column are offset from one another. Previous work on eccentric joints indicates an inferior seismic behavior compared to concentric joints. Beams flush with the concrete column represent the maximum eccentricity considered in previous studies. However, beam–column joints with higher eccentricity where the beam section only partially intersects with the column exist in some buildings. The impact of this notably high beam eccentricity on the seismic performance of joints has not been documented in studies published in open literature to the knowledge of the authors. This paper presents an experimental study focused on a joint geometry characterized by a beam eccentricity exceeding half the column width. The objective is to lay the groundwork for understanding how such eccentricity affects the seismic performance of reinforced concrete beam–column joints. The experiments involved reversed cyclic testing of four large-scale beam–column cruciform assemblages. The results indicate that the joints had sufficient core capacity to develop plastic hinges in the beams. In addition, the tested assemblies exhibited highly ductile behavior and considerable postpeak energy dissipation. The inadequacies of the design documents on such joints are discussed in detail. Based on the findings, a suggestion was made to evaluate the shear strength of such joints. Finally, a strengthening scheme using fiber-reinforced polymer patching was evaluated to improve the seismic performance with minimal work on the joint. The strengthened joint showed similar behavior with a higher energy dissipation compared to the unstrengthened joints. [ABSTRACT FROM AUTHOR]

Axillary bud is an important aspect of plant morphology, contributing to the final tobacco yield. However, the mechanisms of axillary bud development in tobacco remain largely unknown. To investigate this aspect of tobacco biology, the metabolome and proteome of the axillary buds before and after topping were compared. A total of 569 metabolites were differentially abundant before and 1, 3, and 5 days after topping. KEGG analyses further revealed that the axillary bud was characterized by a striking enrichment of metabolites involved in flavonoid metabolism, suggesting a strong flavonoid biosynthesis activity in the tobacco axillary bud after topping. Additionally, 9035 differentially expressed proteins (DEPs) were identified before and 1, 3, and 5 days after topping. Subsequent GO and KEGG analyses revealed that the DEPs in the axillary bud were enriched in oxidative stress, hormone signal transduction, MAPK signaling pathway, and starch and sucrose metabolism. The integrated proteome and metabolome analysis revealed that the indole-3-acetic acid (IAA) alteration in buds control dormancy release and sustained growth of axillary bud by regulating proteins involved in carbohydrate metabolism, amino acid metabolism, and lipid metabolism. Notably, the proteins related to reactive oxygen species (ROS) scavenging and flavonoid biosynthesis were strongly negatively correlated with IAA content. These findings shed light on a critical role of IAA alteration in regulating axillary bud outgrowth, and implied a potential crosstalk among IAA alteration, ROS homeostasis, and flavonoid biosynthesis in tobacco axillary bud under topping stress, which could improve our understanding of the IAA alteration in axillary bud as an important regulator of axillary bud development. [ABSTRACT FROM AUTHOR]