Strategies available for limiting damage arising from accidental actions are:

  • Enhancement of continuity. This strategy consists of the provision of increases in the resistance of the joints of structural members to enhance the effects of continuity on the structure.
  • Strengthening of structure. This strategy consists of the provision of local or general increases in the resistance of structural members to enhance the overall strength of the structure. The strategy will increase the size of the accidental action needed to precipitate failure and will reduce the likelihood of instability. It will not necessarily alter any brittle characteristics of the structure nor the nature of its final failure.
  • Provision of multiple load paths. This strategy requires the design of a structure in such a way that load may be shed into other paths of resistance in the event of a local failure caused by an accidental action. A practical way of checking whether multiple loadpaths are present is to assess whether the structure will remain stable following the notional removal of individual elements in turn. Generally, structures should not be wholly dependent for their stability on the structural integrity of a single connection or element. Where this situation is found during design, the structural form should be re-examined. If the situation cannot be avoided, then particular consideration should be given to the design of the connection or element to ensure that it will have ample strength and toughness.
  • Relief provision. This strategy consists of the inclusion of devices to allow the building to avoid carrying the load resulting from an accidental action.
  • Control measures. This strategy consists of the use of environmental and performance monitoring and control systems. They may be designed so that: 1) the building is used as the designer intended by rapid feedback of information to prevent misuse by the occupants; 2) repair and maintenance is instigated following non-critical damage; 3) accidental actions affecting the structure or building are avoided, e.g. by the installation of bollards, fire compartmentation, fire alarms, etc.