Resumen de Concrete Design Guide No. 2: Eurocode 6: Design of masonry structures for vertical loads
The Concrete Centre
It might seem strange that a series on concrete design should include articles about masonry design. However, much masonry design in the UK uses concrete blocks, made by members of the Concrete Block Association, which is affi liated to the Mineral Products Association.
BS EN 1996 (Eurocode 6) covers the design of masonry for buildings and civil engineering works and is organised into four parts. In common with the other material Eurocodes, Part 1-1 covers the structural design rules1 and Part 1-2 covers structural fi re design2. Thereafter, there is some divergence from other Eurocodes in that Part 2 covers aspects of design, materials and workmanship3 while Part 3 looks after the German need for simplified calculation methods4. Masonry bridges are not covered by EC6. Each part has a corresponding UK national annex5–8.
BS EN 1996-1-1 was fi rst published in 2005 along with BS EN 1996-1-2. BS EN 1996-2 and 1996-3 were published in 2006. The corresponding National Annexes bear the same dates. Corrigenda were issued to Part 1-1 in 2006 and 2009, and in 2012 a new version was published incorporating Amen dment 1. While the 2012 changes to BS EN 1996-1-1 are relatively small, the opportunity was taken to update the corresponding UK National Annex based on feedback from use and recalibration of some of the outcomes. The discussion and observations that follow are therefore related to the 2012 version of the UK National Annex to BS EN 1996-1-1.
A further British Standards Institution (BSI) publication, PD 66979, was published in 2010.
This covers recommendations for the design of masonry structures to BS EN 1996-1-1 and BS EN 1996-2 and encompasses the useful design information previously contained in BS 562810–12, which does not confl ict with the principles contained in EC6.
EC6 has been developed to enable the designer to use the following types of masonry unit: clay, calcium silicate, aggregate concrete, autoclaved aerated concrete (aircrete), manufactured stone and natural stone. European Standards for these materials have been published by the BSI and form part of an array of standards relating to masonry-related products and the associated test methods.
The standards supporting EC6 were developed within a common framework but it did not prove possible to standardise all the test methods used by the diff erent materials from which masonry units are made. Words like ‘brick’ and ‘block’ have disappeared from the European vocabulary and they are all referred to as masonry units.
New methods were introduced for determining the compressive strength of masonry units and the method of determining the characteristic compressive strength of masonry changed from testing storey-height panels to much smaller masonry wallette specimens.
Ancillary components are dealt with in a coherent way within the standards and in BS EN 1996-1-1 suitable values of partial factors have been introduced. The partial factors for use with masonry are given in National Annex Table NA.1 and shown here in Table 15. Two levels of attestation of conformity are recognised: Category I and Category II. This forms part of the declaration made by the manufacturer of the masonry units.
Two classes of execution control are also recognised: 1 and 2.
