Burglary resistance of thermal insulating clay unit masonry (RC 3)

In 2017 the Austrian Clay Masonry Industry carried out a test of burglary resistance according to ÖNORM EN 1627 for the first time. A window was fixed in a highly insulated clay masonry wall (with declared compressive strength of the clay units 7.5 N/mm²). Resistance class RC 3 was verified for the window, the fixing to the wall and the wall itself.     

Shear tests on external clay unit masonry walls / Monolithische Ziegelaußenwände unter Schubbeanspruchung

Monolithic external walls are commonly made of thermally insulated clay blocks that do not require any additional external thermal insulation such as an external thermally insulated composite system (ETICS). To reduce thermal bridge losses, the support length (a) of the slab on the wall is shorter than the wall thickness (t): a < t. The influence on the shear capacity of the respective masonry walls has not yet been tested and analysed. The paper presents the results of shear tests on monolithic external walls with a reduced support length under static‐cyclic and pseudo‐dynamic loading. The test results will be compared with the shear resistance calculated according to DIN EN 1996 with consideration of the German National Annex and the results according to the relevant Technical Approval.     

New approach for spacing of movement joints in reinforced and unreinforced masonry veneer walls / Neue Bemessungsmethode für die Abstände von Dehnungsfugen in bewehrten und unbewehrten Verblendmauerwerksschalen

The first part of the paper, published in issue 4 [3] and dealing with the spacing of movement joints, described the design method for unreinforced masonry veneer walls. This paper focuses on increasing the spacing of movement joints by applying bed joint reinforcement. The proposed approach enables manufacturers of bed joint reinforcement to provide recommendations for the spacing of movement joints for bed joint reinforced veneer walls dependent upon the allowable crack width, the reinforcement type, the diameter and the vertical spacing of the reinforcement.     

New approach for spacing of movement joints in reinforced and unreinforced masonry veneer walls. Part 1: Unreinforced masonry / Neue Bemessungsmethode für die Abstände von Dehnungsfugen in bewehrten und unbewehrten Verblendmauerwerksschalen. Teil 1: Unbewehrtes Mauerwerk

The spacing of movement joints has been subject of many discussions. The current methods for the determination of the spacing of movement joints are based on local traditions and bad experience with cracked veneer walls. This has resulted in various design rules throughout Europe with very stringent limits for spacing of movement joints. According to EC6, one of the solutions for increasing the spacing of movement joints is to introduce bed joint reinforcement, although unfortunately no specific design rules are given. Until now, most scientific research has been focused on numerical simulations without taking time‐dependent effects into account, which is a conservative approach. In this paper, a new approach is described. It is based on Peter Schubert's model and on practical experience with masonry buildings.     

Design of masonry buildings of three‐layered units according to Eurocode 6 / Bemessung von Mauerwerksbauten aus Dreischichtsteinen nach Eurocode 6

In the recent past, the masonry industry has developed many different solutions for optimising the heat protection of buildings. This took place for the building materials, geometric design, but also by development of multiple layered stones in which the components masonry unit, insulation and outer shell have been integrated into a block.     

Non‐loadbearing partitions of unfired clay masonry – Fire behaviour tests

Unfired clay masonry is the most frequently used construction type for residential buildings worldwide, but the long tradition of building with unfired clay masonry in Germany came to an end with the onset of industrialization. The research project EGsL ”Unfired clay masonry: design and construction principles for a widespread use in residential building taking into account climatic conditions in temperate zones with Germany as example location“ is devoted to the preparation of basic principles based on the current state of knowledge about unfired clay as a building material in order to filter out design and construction principles for residential buildings of modern unfired clay masonry. It is assumed that unfired clay has a much better performance capability than is currently expected from the material. The greatest suspicion about the structural safety of unfired clay buildings is based on the water susceptibility of unfired clay, since unfired clay loses its strength under the action of water. In order to improve confidence in the structural stability of residential buildings of unfired clay masonry, a display at the trade fair BAU 2017 showed the basis for an example application of important constructional joints of a theoretical building of unfired clay masonry. As a follow‐up to this, the EGsL research project now intends to demonstrate the fire protection behaviour of unfired clay internal walls in order to ensure the structural stability of unfired clay buildings. The article reports on a first fire test on non‐loadbearing clay masonry walls and describes an example application of non‐loadbearing clay walls in the new Zinzendorf Gymnasium in Herrnhut.     

Einbruchhemmung mit Mauerwerk aus Leichtbeton

Burglary resistance with lightweight concrete masonry The product palette of lightweight concrete blocks ranges from heavy, high‐strength blocks for internal walls, cavity walls and externally insulated (ETICS) external walls to lightweight, highly insulating blocks with lower density and lower compressive strength for monolithic external walls. In the German National Annex to EN 1627, suitable wall constructions for the installation of burglary‐retarding building elements are given. Masonry walls made of heavy, high‐strength blocks fulfil all requirements up to the highest resistance class RC 6. The installation of burglary‐retarding building elements in modern, highly insulating blocks for monolithic masonry is therefore not covered by the standard yet. At the institute for window technology in Rosenheim (ift Rosenheim), testing has been undertaken of the burglary resistance of building elements installed in monolithic masonry made of highly insulating lightweight concrete blocks. For the usual 365 mm thick lightweight concrete masonry units of compressive strength class 2 and density class 0.40 with a lightweight plaster of Type I, the burglary resistance class RC 2 (recommended by the police in Germany) was verified in all the investigated variants of blocks. The results of the research project have been implemented in a proposed change of the German National annex to DIN EN 1627.     

Central Bus Station,Kiel: a perforated brick facade for the parking block

On the occasion of the Olympic sailing competitions in Kiel, the ZOB and the multi‐storey car park above it were built in 1972. The two‐storey multi‐storey car park, equipped for about 560 parking spaces, was originally connected to the railway station quay, the main railway station and the city centre by three pedestrian bridges. These bridges were demolished over the years. The new construction of the Atlantic Hotel in 2009 made it necessary to partially demolish the multi‐storey car park and the ZOB. At the same time, preparations began for the redesign of the remaining ZOB site. However, the original idea of renovating the building, which had been reduced in size by the construction of the new hotel, and additionally increasing it by two parking levels, was rejected. The poor structural condition and the planning of a new attractive bus station ultimately required demolition. In the new planning of the ZOB, two construction sites were defined. The design for the new multi‐storey car park on construction site 2 took into account the specifications for the number of storeys, the spacing areas, the maximum eaves height and the materials used in the neighbouring buildings as an independent building. The rounding of the facade at Stresemannplatz gives passers‐by coming from the west a clearer view of the harbour. The spindle, which is raised above the 6th floor, serves as a recognizable point visible from afar.     

Fixing of windows with fall protection / Befestigung von absturzsichernden Fensterelementen

Glass areas in modern building are becoming ever larger and in refurbishment, window openings are sometimes enlarged. Window elements with fall protection are often used, which undertake the additional function of fall protection, for example of a handrail. Furthermore, opening casements over the entire window height are often installed and “French balconies" of metal are replaced, for example, by appropriate glass panel fillings screwed directly to the window frames. This means that the fixing of the window frame is as important as that of glazing with fall protection. The article describes the current status of this subject and explains fixing into the structure.     

Experimental determination of the load‐bearing capacity of a reinforced perforated brick facade

For a new multi‐storey car park over the Central Bus Station (ZOB) in Kiel, a perforated clinker brick veneer facade not conforming to standards was planned. The design and technical characteristics of the facade have already been described in the article by Medzech and Schrade in this issue [1]. This article deals with the experimental investigations carried out to obtain a project‐related one‐off approval (ZiE). These experiments contain in particular large tests on storey‐height wall sections, which were subjected to eccentric compressive loading and partly to horizontal loads representing wind action. Supplementary small tests on unreinforced and reinforced masonry served to determine the bending capacity, the anchoring capacity of the reinforcement and the load‐bearing capacity of the wall anchors in the masonry. Due to the special facade construction with special bricks for the project, wall anchors, reinforcement bar couplers and unique test set‐ups had to be developed for the specific project.     

High‐rise concrete and clay block masonry building in Brazil

Brazilian structural concrete and clay block masonry construction shares many common features with construction all over the world: blocks of a similar shape are bedded in mortar, vertical and horizontal reinforcement is placed in grouted cells, engineering analysis and design follows universal principles and local design codes mimic those adopted elsewhere. However, loadbearing masonry construction in Brazil has become one of the most preferred high‐rise building systems due to its cost‐effectiveness and ease of construction compared to normal reinforced concrete solutions. This paper provides an overview of loadbearing masonry building in Brazil, including case studies on notable high‐rise masonry structures, with an overview of how Brazilian materials, codes and practices differ from the rest of the world. Finally, the paper explains how the use of high‐strength units assists the growing demand for taller and taller buildings and provides insight into why owners and general contractors often prefer to use structural masonry.     

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.     

Innovative insulation technology for the reduction of thermal transmission losses in cavity walls

The German energy‐saving regulations (EnEV) are continuously revised to make the statutory requirements for thermal insulation of new buildings more stringent, which results in an increased need for highly effective insulation systems. The objective of a research project being carried out at the TU Dresden, Faculty of Architecture, Chair of Structural Design is to solve the problem of reducing thermal losses from masonry buildings through the development of an innovative insulation and fixing system for cavity wall building. The newly developed insulation system should fulfil the essential requirements regarding geometry, loadbearing capacity, flexibility, lifetime and capability of dismantling as well as current requirements for energy saving to ensure the zero energy standard. The research project is mainly based on the use of vacuum panels (VIP vacuum insulated panels) as the central insulation layer in cavity masonry walls and the development of a linear tie system [1], [2].     

Bauakustische Bemessung von Mehrgeschossbauten mit monolithischen Ziegelaußenwänden

Acoustic design of multi‐storey buildings with external walls of monolithic clay masonry For masonry buildings with monolithic, highly insulated walls of clay units, no acoustic design according to standard was practically possible under Supplement 1 to DIN 4109:1989. Therefore a design procedure regulated by approvals was introduced in 2010, with which acoustic calculations for a building could be performed with a high security of forecasting. This procedure has been taken up in the completely revised series of standards DIN 4109:2016/2018 “Sound insulation in buildings”. The basis for the application of this method is knowledge of the individual sound insulation quantities and joint sound insulation quantities for the relevant clay masonry products or product combinations. In order to simplify performance of the verification for clay masonry buildings, the clay masonry industry provides the program “Modul Schall 4.0” (Acoustic module 4.0), in which the decisive acoustic parameters of external wall products from numerous clay masonry unit producers are stored in a database. In this report, experience of application of the design procedure for clay masonry buildings is presented. There is good agreement between forecasts and tests on completed buildings.     

Reliability of masonry walls subjected to in‐plane loading: A slip failure along head joints / Zuverlässigkeit von Mauerwerkswänden bei Belastung in der Ebene: Versagen entlang der Stoßfugenflucht

Masonry structures are a sustainable, economical and traditionally widely used type of construction. However, current masonry design codes are rather conservative, so there is a growing need for revision i.e. calibration of safety factors to improve the allocation of material resources. In this paper, we investigate the probability of occurrence of slip failure along head joints (perpends) in masonry subjected to in‐plane loading. An appropriate limit state function is established and the masonry material properties and loads are defined as random variables in order to simulate likelihood of occurrence of a slip failure regime along the head joints. Furthermore, an example of masonry wall with probabilistic analysis outcomes using Monte Carlo simulation is presented and recommendations for further work are provided.     

Dry laying of masonry to build demountable,highly energy‐efficient prototype houses – First findings from a currently running research project

In recent decades, energy efficiency has been the priority for masonry buildings in order to keep up with ever more stringent requirements. For the evaluation of the sustainability of building solutions, however, the embodied energy to produce a building and finally to dispose of it at the end of its lifecycle are also important. The energy used for the disposal of a building and the processing of the residues are also important for the overall energy balance since the handling of natural resources is increasingly the centre point of thought and action. A research team at the Chair of Structural Design of TU Dresden has thus been working since 2012 on demountable solutions in masonry, which can be dismantled at the end of a building lifetime and sorted for recycling, which fully complies with the requirement for the reduction of rubbish and waste products. The high precision of block production today permits us to omit the levelling effect of mortar and to build dry buildings in the future, i.e. to do without the bonding principle. The associated strength reductions can be suffered without problems. The appropriate basics of such a dry building method have been researched in a collaboration between the ILEK in Stuttgart and the Xella Technologie‐ und Forschungsgesellschaft mbH in Emstal. In this research project with the abbreviation ”REMOMAB“, the basics of an energy‐efficient dry building method suitable for recycling were collected and made available for practical application. In a follow‐up project, these basics are being implemented and tested on an experimental building. Cost aspects are also to be taken into account and if possible, construction solutions available on the market will be used – modified if necessary. Another aim is for the first time to dismantle such a building and to rebuild it at another location. This is intended to demonstrate that a reuse is possible after dismantling and such a building method can react to changing demands in the housing market.