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.
Ultimate Strength of Ribbed Slab Composite Beams with Web Openings
A series of tests is performed on composite beams with web openings. The beams have ribbed slabs with the ribs oriented transversely. The effects of slab width and moment-shear ratio on failure mode and strength are studied. Failure mode of concrete slabs depends on the slab width. Pullout failure around the shear connectors at the high-moment end occurs in the beams with wide slab width, while diagonal tension-type failure occurs in a beam with narrow slab width. Based on the test results, a strength model is developed. The maximum shear capacity is approximated as the sum of the individual shear capacity of the steel beam and the concrete slab. The shear contribution of the concrete slab is taken as the lesser of the shear strength of the slab and the pullout capacity of the studs. Strength predictions of the proposed model are compared with test results and predictions of other strength models. The proposed model is easy to use and gives satisfactory predictions.
Joint strength of aluminum ultrasonic soldered under liquidus temperature of Sn–Zn hypereutectic solder
Abstract In order to obtain high-strength aluminum joints, ultrasonic soldering of 1070 aluminum was conducted under liquidus temperature of Sn–Zn hypereutectic solder. A device for ultrasonic soldering was assembled, which propagated ultrasonic vibrations in a direction perpendicular to joining surfaces. This device joined 1070-Al using quasi-melting Sn–Zn hypereutectic solder without using any artificial spacers. The strength of the solder joints was evaluated by tensile tests. The optimum joining conditions were determined, and the effects of solder compositions and soldering temperature on the joint strength and the solder layer thickness were examined. In this ultrasonic soldering process, the highest tensile strength was obtained for the solder joints fabricated at 220 °C for the Sn–23Zn and Sn–40Zn solder compositions. The joint strength was equivalent to that of 1070-Al heat treated at 220 °C. The sound joints were obtained at 300 °C using Sn–82Zn solder, the liquid phase volume fraction of which was theoretically only 0.24. The present work also revealed that the thickness of retained solder layer in the joint after ultrasonic soldering could be estimated. Accordingly, ultrasonic soldering under the liquidus temperature of Sn–Zn hypereutectic solder could be a spacer-free soldering method to obtain high-strength aluminum joints.