N°226. 1995. Design of Fastenings in Concrete - Draft CEB Guide Part 1 to 3 - Fastenings for Seismic Retrofitting - State-of-the-art Report on Design and Application.

Modem fastening technique is increasingly employed for the transfer of concentrated loads into concrete and masonry structures. Cast-in-place systems (which are placed in the formwork before casting of the concrete) and post-installed systems (which are installed in hardened structural concrete or masonry) are equally common.

The load is transferred into the base material by mechanical interlock, friction, bond or a combination of these mechanisms. In general independent of the load-transfer mechanism, fastenings rely on the tensile capacity of concrete or masonry.

Although a large number of fastening assemblies are installed every day, understanding in the engineering community about their behavior is generally very limited. Furthermore, there is no generally accepted design method.

In order to improve the genera} knowledge and awareness of the engineering profession in this area, Task Group 3.5 'Fastenings to Concrete and Masonry Structures' was formed by CEB in 1987.

The group produced a state-of-art report on fastenings to concrete and masonry structures, first published as Bulletins 206 and 207 in 1991 by CEB and in a revised version as a book by Thomas Telford in 1994. Since then the Task Group has concentrated on two topics:

(1) Guide for the design of fastenings in concrete

(2) State-of-art report on design and application of fastenings for seismic retrofitting

Meetings have been held in the following locations:

Abisko (June 1992)

San Juan (October 1992)

Santorini (May 1993)

Prague (November 1993)

San Francisco (March 1994)

Artes (September 1994)

Kyoto (May 1995)

In the following a draft guide for the design of fastenings in concrete is proposed and the use of fastenings in seismic retrofitting is reviewed. Both reports will be presented to the 30th CEB Plenary Session in September 1995.

The draft design guide is based on the safety concept of partial safety factors and covers all loading directions and failure modes. It takes into account the current state of the art and is valid for expansion, undercut and headed anchors. lt is applicable to both new construction and the repair and strengthening of existing structures. In the future, the guide will be extended to cover fastenings with bonded anchors, channel bars and shear lugs as well as applications subjected to seismic excitations.

The state of the art report on design and application of fastenings for seismic retrofitting provides a review of the design concepts and methods for seismic retrofitting, with emphasis on the use of fastening systems applied for retrofitting of reinforced and masonry buildings. lt also serves as the basis for a design guide for fastenings in seismic retrofitting currently in preparation.