Introduction - Strengthening of Concrete Structures with Adhesively Bonded Reinforcement - page 1

1 Introduction

1.1 The reason behind this topic
The main reason is the revised approach to the design of adhesively bonded strength-
ening measures for concrete members given in the guideline [1] (q.v. [2]) published by
the Deutscher Ausschuss für Stahlbeton DAfStb (German Committee for Structural
Concrete). This topic explains the design rules of the DAfStb guideline, together with
their background, and uses examples to illustrate their use. The scope of the explanations
and background information provided here is mainly based on works that have already
been published. However, some rules that so far have been dealt with in detail in
committee meetings only are elaborated here for the first time.

1.2 Strengthening with adhesively bonded reinforcement
The strengthening of concrete members means using constructional measures to restore
or improve their load-carrying capacity, serviceability, durability or fatigue strength.
The effects of strengthening measures can generally be described in quantitative terms
and therefore analysed numerically. Besides numerous other methods (see [3, 4], for
example), the subsequent strengthening of existing concrete members can be achieved
by using adhesives to bond additional reinforcing elements onto or into those members.
This topic of reinforcement bonded with adhesive has been the subject of many
contributions to various editions of the Beton-Kalender in the past (see [5, 6]). However,
design approaches for adhesively bonded reinforcement have continued to evolve
(see [7, 8]) and the new DAfStb guideline [1, 2] on this subject revises those design
methods and adapts them to our current state of knowledge. In principle, the DAfStb
guideline together with a corresponding system approval allows the following concrete
member strengthening measures to be carried out:
- Flexural strengthening with externally bonded (surface-mounted) CFRP strips, CF
sheets and steel plates
- Flexural strengthening with CFRP strips bonded in slots (near-surface-mounted
reinforcement)
- Shear strengthening with externally bonded CF sheets and steel plates
- Column strengthening with CF sheets as confining reinforcement.
Figure 1.1 provides an overview of these methods. The term 'adhesively bonded' is used
in this topic as universal expression comprising both methods

' externally bonded ' and

' near-surface-mounted ' .