Connection design resistance

It is important that connections for blast loaded members have sufficient rotation capacity, A connection may have sufficient strength to resist the applied load however, when significant deformation of the member occurs this capacity may be reduced due to buckling of stiffeners, flanges, etc. Figure 10.1 is an example of a connection design for large rotation capacity. 

P(l) All connections shall have a design resistance such that the stmcture remains effective and is capable of satislying all the basic design requirements given in Chapter 2. 

Anodes are connected to the object to be protected or to the transformer-rectifier by insulated conductors that are resistant to mineral oil (e.g., Teflon-coated cable) with a cross-section of 2.5 mm of Cu. The transformer-rectifier must meet the demands according to Ref. 6 and have the capability for monitoring and controlling its operation. The life of the anodes is in every case designed to be at least 15 years. 

In practice the loss for an iron anode is approximately 9 kg/Ay. Thus consumable anodes must be replaced at intervals or be of sufficient size to remain as a current source for the design life of the protected structure. This poses some problems in design because, as the anode dissolves, the resistance it presents to the circuit increases. More important, it is difficult to ensure continuous electrical connection to the dissolving anode. 

In all blast-resistant structures (steel, concrete, or masonry) special attention should be given to the integrity of connections between structural elements up to the point of maximum response. For example, it is important to prevent premature brittle failure of welded connections to avoid stress concentrations or notches at joints in steel structures and to provide ductile reinforcement detailing in concrete/masonry structure connections. For all materials, it is recommended that connections be designed to be stronger than the connected structural members such that the more ductile member will govern the design over the more brittle connection. 

Furthermore, a cell header with its 70-100 connections is not easy to replace, and considerable numbers of safety features have to be incorporated into its design. Composite materials do not lend themselves to effective non-destructive testing and a leaking joint may lead to delamination of the chemical-resistant liner from its mechanical support. Since any leaks cannot be detected easily in such circumstances, the entire header must be replaced with a corresponding electrolyser downtime. 

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