Design according to Eurocode 6 in practice

For the structural design of masonry according to Eurocode 6 with the associated German national annex, the simplified method and the further simplified calculation method in Annex A are available. These procedures provide tools that can be used in practice to design standard cases quickly and easily. One feature of the verification of masonry walls under compressive loading is that no bending moments in the walls have to be determined as part of the determination of section forces and moments since the verification of the load‐bearing capacity of the wall is based solely on the acting vertical force. The effects of floor end restraint and buckling are dealt with by simple equations. One new feature of verification according to Eurocode 6 is that the effect of partially supported floors on the load‐bearing capacity of the wall can be included directly. The code is compact and simple to use and the further simplified calculation method is predestined for verification by manual calculation.     

CJEU Judgment,Standardisation and Eurocode 6 / EuGH‐Urteil,Normung und Eurocode 6 – Aktuelle Fragen im Mauerwerksbau

This article reviews current challenges for the masonry industry from a regulatory perspective. First, the CJEU judgment and its consequences will be discussed. The judgment of 16 October 2014 will make fundamental changes in the German regulatory system necessary. How these will be implemented is not yet clear so that this article can only give an overview of the present situation (September 2015) in the discussions. What is clear is that the changes in the regulatory system will have repercussions in the field of standardisation. These repercussions will be outlined – in general and specifically for the masonry sector – in the second part of this article. Finally, the paper will look at the progress in the implementation of Eurocode 6 (Design of masonry structures).     

Buckling of masonry walls – A new proposal for the Eurocode 6

The buckling of masonry wall depends on the deformation behaviour and can be described with the modulus of elasticity depending on masonry strength. The reduction factor solution considering buckling is described by the Gaussian bell‐shaped curve in Eurocode 6, Part 1‐1 Annex G and was calibrated for masonry with a modulus of elasticity between 700 and 1000 f_k, which describes the masonry currently used in most European countries. In case of historic masonry or where deformability is needed in new construction, the modulus of elasticity can actually be lower. In those cases the approximation procedure according to Annex G of the Eurocode 6 delivers results which do not represent the real behaviour and leads to uneconomical results. The present paper proposes a new empirical method, which can be applied over the whole practical range of the elastic modulus of masonry. The new proposed method has been verified with experimental data and shows a very good fit.     

The simplified calculation method of DIN EN 1996‐3 in practice / Das vereinfachte Bemessungsverfahren von DIN EN 1996‐3 in der Praxis

The design and detailing of masonry buildings was usually undertaken in the past using the simplified procedure in Section 6 of DIN 1053‐1 (1996‐11). With the changeover to the new European code, a new procedure has been made available with the simplified calculation method of DIN EN 1996‐3, which promises similarly simple and safe handling for the user. The practical implementation of this new code has been underway for some time. The article investigates the standard design cases and explains the innovations and alterations compared to DIN 1053‐1.     

Flexural tensile tests with vertically perforated clay unit masonry with thin layer mortar / Biegezugversuche an Planziegelmauerwerk

As part of the EU project, INSYSME – INnovative SYStems for earthquake resistant Masonry Enclosures in reinforced concrete buildings – to optimise infill masonry the German project partners carried out an initial part of the project on flexural strength testing of high‐tech clay block masonry in accordance with DIN EN 1052‐2. In this a wide range of modern products was considered which at present is regulated in Germany by means of general building authority approvals. The test results show that the specifications for flexural tensile strength of high‐tech clay block masonry in DIN EN 1996 are very conservative in most cases.     

Determination of a model partial safety factor for unreinforced masonry walls under buckling

The design/verification method in the Eurocodes is based on the partial safety concept. Eurocode 6 suggests a constant partial safety factor for the material γ_M for all design/verification problems, without consideration of model uncertainty in the design/verification formula. In the following, a model partial safety factor is determined for the problem of unreinforced masonry walls mainly subjected to vertical loading. For that purpose, the newly proposed formula for EC 6, annex G will be considered [1–3]. In order to cover all aspects in tests and to use the results for design purposes, several methods have been included in EN 1990 Annex D for design based on test data. In this study, the recommended methods in Annex D of EN 1990 for resistance of the material are used to extract the partial safety factors. A database including more than 119 experimental tests on unreinforced masonry shear walls is used to compare the model prediction and the test results and to determine the model partial safety factor.     

Analysis and comparison of the NDPs of various national annexes of Eurocode 6 / Analyse und Vergleich der NDPs verschiedener nationaler Anhänge zu Eurocode 6

In the national annexes of Eurocode 6, the individual European Member States can define values for nationally determined parameters in various places or add regulations which are not in contradiction to the current European provisions. Consequently – despite a harmonized Eurocode 6 – the normative regulations of the individual Member States differ more or less. However, in the sense of practicability of the standards in Europe, it should be the aim to develop a European standard which is as uniform as possible and which has not to be applied in significantly different ways due to the national regulations. In order to better understand the interests of the other Member States for future generations of standards and to derive potentials of harmonization, the values of the Nationally Determined Parameters (NDPs) of various Member States are compared in this paper. In this context, the extent of the deviations between the different national annexes is examined and on this basis a possible potential of harmonization is identified.     

Sustainable building with masonry / Nachhaltiges Bauen mit Mauerwerk

Ecology, energy and sustainability are crucial socio‐economic keywords, especially for the construction and real estate industry. In recent years, the masonry industry faced related sustainability issues intensively in order to keep its ability of operating in a market setting which is increasingly characterized by sustainability dogmata. Scientific analyses and studies on an objectified sustainability basis – such as established certification systems – show that masonry is absolutely competitive with all other market‐relevant construction methods. Therefore, the first part of this paper deals with a sustainability assessment of buildings made of masonry as well as of other construction materials. Concerning the design and construction of masonry, further selected aspects are discussed which are important for the competitiveness of this building technique. Outlining the simple yet economic pre‐dimensioning with the help of load capacity tables is one topic which is of utmost importance for an efficient structural design. Additional aspects are the design of laterally loaded exterior walls with low vertical forces and the verification of basement walls under high earth pressure load. New and easy to use design proposals are open for discussion. Finally, the educational portal “masonry structures” of the Deutsche Gesellschaft für Mauerwerks‐ und Wohnungsbau (DGfM) (German society for masonry and residential construction), which supports the training of young engineers, is presented.     

Tragfähigkeitserhöhung bei Mauerwerk durch textilglasgitterverstärkte Mörtelfugen

Increase of the vertical load carrying capacity of masonry due to mortar bed joints with textile glass mesh reinforcement From a structural point of view, one of the most important material parameters in the construction sector is the vertical compressive strength of masonry, which consists of the compressive strength of the bricks as well as of the mortar bed. The interaction between the bricks and the mortar beds is the main reason for compression failures of masonry walls. A close analysis of the deformation behavior of the two components shows that different transverse strains in the contact surface between the bricks and the mortar are the main cause for compression failures. However, the load‐bearing capacity of masonry walls can be increased by using some reinforcement in the mortar beds which counteracts lateral expansion. The impact of textile glass mesh reinforcement on the load‐bearing capacity of masonry was analyzed in a test program on masonry columns with different numbers of textile glass mesh reinforced mortar beds. The results of the analyses show that the load‐bearing capacity of the columns rises with an increased ratio of reinforcement, regardless of the type of bricks used. From the ratio of the height of the reinforcement layers to the thickness of the wall it can be deduced that a higher degree of reinforcement has a positive effect on the load‐bearing capacity of the masonry. On this basis, an increase of the strength and load‐bearing capacity of masonry walls is formulated to be on the safe side.     

Analysis of steel‐reinforced masonry walls regarding maximum shear loads / Traglastberechnung von vertikal bewehrten Mauerwerksscheiben

Loadings on masonry for the earthquake case pose particular challenges for the material. In order to improve the load‐bearing and deformation behaviour, masonry building elements can be strengthened with reinforcement. This article presents an analytical model for the calculation of the load‐bearing capacity of vertically reinforced masonry panels. The masonry is modelled as a homogeneous and anisotropic material and failure conditions are based on the plastic theory. Using uniaxially loaded stress fields and considering the structural constraints, a lower load‐bearing threshold can be given. In order to verify the model, three shear tests on reinforced sand‐lime block masonry were recalculated regarding their load‐bearing capacity. The test panels each contained vertical steel reinforcement in the blocks. The blocks were laid in thin bed mortar.     

Zerstörungsarme Bestimmung der Steindruckfestigkeit von Bestandsmauerwerk aus Hochlochziegeln

Non‐destructive determination of the compressive strength in existing masonry made of vertically perforated bricks Urban consolidation and the conservation of listed buildings often require measures to determine the structural stability of the existing masonry. The key parameter for the static proof is the compressive strength of the masonry, which consists of the compressive strength of the bricks and the compressive strength of the mortar bed. So far, no testing methods have been developed that do not significantly interfere with the static load bearing capacity of masonry made of vertically perforated bricks and which make it possible to determine the compressive strength by analysing parts of the bricks. This article presents a non‐destructive test method to determine the compressive strength of vertically perforated bricks of existing masonry. This test method only uses small test specimens taken from parts of the bricks. As a result, the static load bearing capacity of the existing masonry is hardly affected. The results of these tests show that it is possible to establish a plausible correlation between the comprehensive strength of the brick and the compressive strength of the small test specimens. On this basis, a concept for a non‐destructive testing method which makes the determination of the compressive strength of vertically perforated bricks in existing buildings possible is presented.     

Shear tests on full scale storey‐height specimens constructed with thermally insulating clay unit masonry with thin‐layer mortar

The paper presents results of a series of 6 in‐plane shear tests on storey‐height clay unit masonry panels [1] with thin‐layer mortar, carried out in addition to previous test campaigns [2], [3], and [4]. The walls were constructed with unfilled thermally insulating clay units with a thermal conductivity of λ = 0.09 W/(m · K). The current design rules for clay unit masonry according to DIN EN 1996‐1‐1/NA [5] are conservative compared to the presented test results for thermally insulating clay unit masonry.     

Experimental investigation of masonry arches exposed to horizontal impact / Experimentelle Untersuchungen von Mauerwerksbögen unter Horizontalanprall

Abstract: Arch bridges still form a large part of the bridge stock in German‐speaking countries and in Europe. In general, they have a high loadbearing capacity for vertical loads. However, only a limited number of research investigations into the capacity of these bridges to resist horizontal impact have been carried out. In this paper we describe static and dynamic tests for the evaluation of the loadbearing capacity of masonry arches exposed to horizontal loads in transverse direction. Furthermore, a simple engineering model is developed for such load cases.