Design of composite beams with web openings
Summary Design techniques for composite beams with web openings have been under development for well over 30 years. During the past decade, these efforts have reached a level of maturity that allows for an accurate assessment of strength and the development of economical designs. This paper describes the behavior of steel}concrete composite beams with web openings and summarizes the key aspects of strength design and deflection calculation.
Web Openings in Composite Beams with Ribbed Slabs
Fifteen tests to failure are performed on full-scale composite beams with web openings. The beams have ribbed slabs that use formed deck steel. The ribs are perpendicular or parallel to the steel section. The effects of moment-shear ratio, quantity, and placement of shear connectors, deck orientation, and deck thickness are studied. The concrete slab contributes significantly to both the flexural and shear strength of beams at web openings. Peak loads are governed by failure of the slab. Rib failure around shear connectors occurs in slabs with transverse ribs, while longitudinal shear failure occurs in slabs with longitudinal ribs. Strength at an opening increases as the shear-connector capacity above the opening and between the opening and the support increases. The implications for design are discussed.
Shape and surface texture of molten droplets deposited on cold surfaces
When a molten droplet impacts on a cold surface, the interaction between solidification and fluid dynamics can lead to different shapes and surface textures of deposited droplets. This article presents an experimental study on deposition of small droplets (39 μm diameter) of molten wax ink on solid surfaces. Our results show that both the final shape and the surface texture of deposited droplets are extremely sensitive to deposition conditions, which include initial temperature of droplets, type of substrate surface and distance between substrate and printhead. Different surface textures are observed and shown to depend on the thermal and flow histories of ink droplets during the process of impact. A test using crystalline wax reveals crystallization as one of the major factors in determining the final texture.