State-of-the-art review on the design and performance of steel pallet rack connections

Steel pallet racks (SPRs) are used in the industrial buildings, warehouses and superstores for storing a multitude of different kinds of goods. Because of changing needs over the years, it is often desirable that such installations be readily demountable and capable of reassembly. Therefore, the beam-to-column connections (BCCs) used in SPRs are boltless in nature. SPR BCCs govern the stability of the frame in the down-aisle direction. The design of SPR BCCs is one of the problems for designers that cannot be handled routinely within the existing design specifications available for bolted and welded connections. Moreover, the studies on the considerations necessary for the design and performance of SPR BCCs solely are rarely available. It is therefore, essential to bring to light the factors that play significant role to improve the design and performance of SPR BCCs. A critical review of the research performed over the last few decades into the global stability of SPR structures in the down-aisle direction only is presented in this paper. The information about the design methodologies and testing procedures defined in the literature and design codes as well as the factors governing the performance of boltless connections are identified. The major failure modes are highlighted. The characteristics of the main elements constituting SPRs are also succinctly discussed. Based on the findings, the limitations of current study are highlighted and future research areas are identified

Tooth wear against ceramic crowns in posterior region: a systematic literature review

The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against ceramic crowns in posterior region. The selected studies were analyzed in regard to type of crowns, natural antagonist, measuring protocol and outcome. From a yield of 1 000 titles, 43 articles were selected for full-text analysis; finally, no in vitro and only five in vivo studies met the inclusion criteria. As there is heterogeneity in design, used measuring method, ceramics and analysis-form, a meta-analysis was not possible. Results of these studies are very controversial which makes a scientifically valid comparison impossible. This review indicated that some all-ceramic crowns are as wear friendly as metal-ceramic crowns. Up to now, it has been impossible to associate tooth wear with any specific causal agent. The role of ceramic surface treatment that might be responsible for the changing in rate of tooth wear seems undetermined as yet through clinical trials. The literature reveals that studies on this topic are subject to a substantial amount of bias. Therefore, additional clinical studies, properly designed to diminish bias, are warranted