5. STRUCTURAL DESIGN OF CONNECTIONS Figure 5.2. Edgewise (edge face) and flatwise (wide face) orientations and loading types of connections. Fax,d are forces of axially loaded and Fv,d are forces of laterally loaded connections 34. Figure 5.3. A) Laterally loaded connection 34 B) Axially loaded connection. 5.1 DESIGN OF LVL CONNECTIONS ACCORDING TO EUROCODE 5 The design of connections with metal fasteners is specified in Section 8 of Eurocode 5. However, the design instructions do not fully cover LVL products. This section therefore provides additional definitions for LVL based on the following documents: • Design rules for LVL to Eurocode 5, Proposal for discussion in CEN/TC250/SC5, Prof. Dr.-Ing. H.J. Blaβ and Dr. –Ing.M. Flaig, Blaβ & Eberhart GmbH, 30.6.2017, CEN/TC250/SC5/ N0764 32 • Finnish Handbook for Eurocode 5 (RIL205-1:2017, Puurakenteiden suunnitteluohje) 31 • Connection chapters of Metsä Wood Kerto Manual 34, 35 The equations in this Section have individual numbers and when an equation is in the same form in Eurocode 5, it is marked with EC5 and the equation reference number there, e.g., (EC5 8.2). For the connection design of LVL members it is essential to note that the behaviour of the product may differ depending on whether the connections are on the wide face (flatwise) or on the edge face (edgewise) of the LVL, see Figure 5.2. The edge face of LVL is more sensitive to splitting, which must be taken into consideration when determining the geometry and maximum fastener sizes of connections. LVL-C, on the other hand, has the advantage of ductile behaviour of connections on the wide face due to its cross veneers, thus eliminating a number of wood failure modes related to connections and enabling denser groups of fasteners. A connection may be laterally loaded, axially loaded, or both laterally and axially loaded. For the determination of the characteristic lateral load-carrying capacity of connections with metal dowel-type fasteners, the contributions of the yield strength, embedment strength, and withdrawal strength of the fastener shall be considered. Section 8.2 of Eurocode 5 provides equations for calculating the characteristic load-carrying capacity of nails, staples, bolts, dowels and screws for different failure modes according to the Johansen yield theory. The minimum value, based on the relevant failure modes for the connection type, should be taken as the capacity per shear plane per fastener. Fastener type specific instructions for calculating the embedment strength fh,k ,yield moment My,Rk and axial withdrawal capacity Fax,Rk, which are needed for the capacity calculation of laterally and axially loaded connections, are defined in sections 8.3-8.7 of Eurocode 5. Alternatively, fastener suppliers provide their own design instructions for connections using their products in their ETA assessment documents. A B LVL Handbook Europe 143
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