Reinforcement specifications of antiseismic design

Reinforcement specifications of reinforced concrete earthquake resistant structures include the detailing specifications applied to conventional structures as well, since earthquakes occur very rarely in the structures’ life span.

For a structure to be earthquake resistant it must firstly abide by the regulations regarding usual structures. However, its construction demands greater attention because the critical moment of the seismic event will test the structure’s strength capacity thus proving the need for meticulous application of all the regulations referring to reinforced concrete. Apart from the normal con-struction rules, other rules must be satisfied as well mainly regarding the vertical reinforcement like use of narrow spaced polymorphic stirrups.

The construction specifications regarding the formation and placement of reinforcement are mandatory for all structures since they are issued by Eurocodes, and specifically by EC2, for reinforced concrete design, and EC8 for seismic design. A technician most of all must compre-hend their necessity and based on that must always perform his/hers practices in compliance with them. The best way of avoiding mistakes and errors in construction is training and supervi-sion accompanied by the knowledge of the legal rules.

In earthquake resistant structures the requirement for a large amount of narrow spaced longitu-dinal and vertical reinforcement makes elements reinforcing a quite strenuous task. If in coun-tries with low seismic activity the requirement for correct design implementation is taken as a fact, in earthquake prone countries, like Greece, this requirement is at least two times more im-portant.

The basic specifications of seismic reinforcement are four:

(1) The reinforcement covering

(2) The minimum distance between reinforcement bars

(3) The minimum possible bending of rebars

(4) The stirrups