WCTE 2016

Die World Conference on Timber Engineering (WCTE) – die weltweit wichtigste Holzbaukonferenz, die seit 1996 alle 2 Jahre abwechselnd in Nordamerika, Asien und Europa stattfindet, fand vom 22. bis 25. August 2016 in Wien statt.

Als Organisatoren der Konferenz fungierte ein interdisziplinäres Konsortium aus den Fachrichtungen Architektur und Bauingenieurwesen der Technischen Universität Wien – Prof. Wolfgang Winter und Prof. Josef Eberhardsteiner. Das Konferenzprogramm für die WCTE 2016 bestand aus knapp 800 Vorträgen – 350 in den zu speziellen Themen organisierten Mini-Symposien, mehr als 200 in den aus den Conference Topics zusammengefügten General Sessions sowie 190 Posterpräsentationen. Die Beiträge von und unter Mitarbeit des ITI sind folgend kurz (in Englisch) zusammengefasst:

Development of prefabricated timber-steel-concrete ribbed decks

W. Winter, K. Tavoussi, A. Fadai, F. Riola Parada, I. Prasnjak

Timber-steel hybrid beams have already been proposed, tested and analyzed for their use in frame multi-storey buildings. Although these beams can be combined with any type of structural floor, their use with concrete decks opens the door to new and promising structural strategies. Present-day timber-concrete floors are a good solution for contemporary multi-storey buildings. They provide in-plane stiffness, enough mass for sound isolation and can be optimized from a structural performance point of view. Meanwhile hybrid beams could provide lightness, reduced structural depth, reduce the creeping behaviour and make frame semi-rigid joints easy to build. The goal is therefore the development of a combined system of hybrid beams and concrete floors, proposing prefabricated or semi-prefabricated timber-steel-concrete ribbed elements that could make the most of all this potential. First design concepts and planned tests are presented in this paper.

Timber-steel hybrid beams for multi-storey buildings: final report (Extended Lecture)

W. Winter, K. Tavoussi, F. Riola Parada, A. Bradley

Timber-steel hybrid beams have been proposed, tested and analyzed for their use in multi-storey buildings. After the first concepts and tests were presented in the WCTE 2014, two whole testing series are finished and their results globally presented and analyzed. The beams fulfilled all the expectations and therefore can be presented as a reliable possibility for future proposals of timber-based frame multi-storey buildings. The present paper presents a summary of the part regarding hybrid beams inside the research project “Timber based mixed systems for dense construction in urban areas” carried out by the Institute of Structural Design and Timber Engineering of the Vienna University of Technology.

Enhanced fire behavior of wood-based buildings in social housing

A. Fadai, M. Kist, W. Winter, C. Radlherr

Recent developments in structural design and timber engineering favor the increased use of the renewable resource wood as an alternative, high-performance construction material to meet rising quality demands regarding functionality, durability and fire safety. In several research projects of the Department of Structural Design and Timber Engineering (ITI) at the Vienna University of Technology (VUT) the combination of timber products with other conventional building materials and components was explored with the purpose to fulfill the most stringent fire instructions in the building sector and the fire safety standard requirements. The reported research shows results regarding the fire behavior of wood-based buildings in residential housing and indicates a potentially fire-retarding thermodynamic effect in wood-based composites.

Robotic production of individualised wood joints – addition

B. Çokcan, W. Winter, J. Braumann, R. Krobath

Wood is one of the most traditional materials in architecture, but has gone through significant developments over the centuries and is now perceived as a high-performance material. Before the industrialisation, wooden constructions were planned and produced by carpenters, acting upon the clients’ parameters such as the number of stories, number of rooms and required functions. During the period of industrialisation modularity and mass production dominated the construction industry. Prefabricated panels became the most relevant construction elements. In recent decades, contemporary architecture has turned away from this kind of modularity, instead utilizing digital design methods, CAD/CAM planning and flexible manufacturing technologies to enable new and different forms of modularity. The module of this digital period is defined by its capability of combining unique forms and elements with dynamic manufacturing strategies. Thus, modern modular constructions can consist of highly individualized elements that are produced with nearly the same efficiency as serial manufacturing.

This paper focuses on the project “Addition” – a Pavilion, which was designed with this new concept of modularity, manufactured automatically with a 6-axis robotic arm. New CAD/CAM interfaces, linking design directly with fabrication, enabled the serial production of 450 individual slab joints with 14 different connection angles.

Fire performances of timber-cold formed thin steel plate composite beam

B. Izumi, A. Tani, N. Toba, K. Nakashima, M. Koshihara, T. Yamanashi, M. Kohno, W. Winter

The concept of combining folded thin steel plates and glued laminated timber in the beam element to gain increased structural and fire performances was developed at the Institute of Structural Design and Timber Engineering (ITI) in Vienna University of Technology. The authors conducted non-loaded combustion tests and numerical simulations of the three different types of such cross-sections, and results from combustion tests and numerical simulations are discussed.

A comparative study on ecological impact of timber-glass-façade and conventional facade systems

V. Saleh Pascha, W. Winter

It is crucial to run a Life Cycle Assessment analysis (LCA) in order to evaluate environmental impacts of using different construction materials aiming to find the ways to reduce CO2 emission and greenhouse gases in building sector, which demonstrates a high share of consumption of energy and raw materials as well as related damage to the environment. The newly developed timber and glass composite (TGC) is seen to be highly potential as an ecological alternative to conventional aluminium facade. This paper presents an environmental impact study of the TGC based façade in comparison to conventional façade systems. Moreover, a review of recently published studies on environmental impact of different facade systems is presented together with a discussion of differences in LCA methodologies applied in the studies and their influences on the results.

Timber-glass composites: calculation and sizing concept

W. Hochhauser, A. Fadai, W. Winter, M. Rinnhofer

Glued glass front constructions have been applied for a long time and comply with the state of the art. However, with these solutions, the glass has not a stiffening bearing function, merely functions as an outer cover. The objective of several research projects was to investigate alternative constructions of stiffening glass fronts, which replace St. Andrew’s cross wind bracings and costly frameworks. Therefore, the Department of Structural Design and Timber Engineering (ITI) studied existing and optimized the load-bearing capacity of these construction components, developed simple calculation and sizing concepts. Based on the results of the research project „Timber-glass composites: calculation and sizing concept (HGV III)“ the ITI coordinated the follow-up international research project “Load bearing timber-glass composites (LBTGC)” within the framework WoodWisdom-Net. In consideration of long-term behavior and practical application, the objective of the research project LBTGC was to develop “stiffening timber-glass composites (TGC) structures”. With the purpose to meet the highest standards of cost effectiveness, alternative stiffening TGC constructions for multi-story buildings were investigated. This paper illustrates these developments as well as application of TGC multi-story facades.

Geometrical aspects for the design of prefabricated load-bearing timber-glass-facades

K. Saleh Pascha, V. Saleh Pascha, W. Winter

The considerable increase in the architectural demands for highly transparent and load-bearing structures have recently resulted in the development of an innovative hybrid structure. This article provides a review of design parameters for Timber-Glass composite facades. The design/architectural question, which arose in the project, was how to define the interface of the prefabricated glass-timber-elements with the shell building. Through different design proposals different criteria as admittance of building tolerance and dilatation, load-bearing transfer capacity, maintenance requirements and architectural and design qualities were defined and verified through 3-d-models, prototypes and mock-ups.

Multifunctional composite wall elements for multistory buildings made of timber and wood-based lightweight concrete

A. Fadai, C. Radlherr, S. Setoodeh Jahromy, W. Winter

This paper aims to discuss timber-wood lightweight concrete composites for application in wall components for buildings. The aim is to develop a multi-layer wall system composed of wood lightweight concrete, connected timber sections to gain and use advantages of each used material – lightweight, structural, thermal storage and insulation, ecological and economic benefits – to name the most important ones. The development of timber-wood lightweight concrete composites systems will lead to a new generation of polyvalent multi-material building components. By using renewable resources, waste products of the forest industry, and manufactured wood products, this technology provides statically and energy-efficient components for low-energy constructions. Such products support rapid-assembly construction methods, which use prefabricated dry elements to increase the efficiency of the construction. Wood-based alternatives to conventional concrete or masonry construction also open opportunities to reduce the carbon emissions.

Timber-glass composite beams: experimental study

A. Fadai, M. Rinnhofer, W. Winter

Glued glass fronts are extensively applied and meet the highest standards. The objective of several research projects was the development of stiffening glass fronts to replace expansive frameworks or wind bracings. Furthermore, the use of timber-glass composite (TGC) beams was investigated. Within the research project "Load Bearing Timber-Glass Composite Structures” (LBTGC) within the framework WoodWisdom-Net the short-term behavior of TGC-beams was investigated. Therefore, the Department of Structural Design and Timber Engineering (ITI) developed a beam-setup to test the load-bearing capacity of such elements under a four point bending test. Two different adhesives, silicone and epoxy, were used to connect timber and glass. The two adhesives vary in their strength and their stiffness. This has an immense influence on the behavior of the beams. This paper illustrates the results of various applications.

Wood lightweight concrete composites structural elements: ecological impact

A. Fadai, A. Borska, W. Winter

Within several research projects and with the aim to optimize energy efficiency and ecological characteristics of structural building components the Department of Structural Design and Timber Engineering (ITI) at the Vienna University of Technology (VUT) developed several wood-based composite systems, which combine timber products with other conventional building materials and components. As a representative example for these developments, the application of wood lightweight concrete composites illustrates the extent of interrelationships in the development of complex system solutions when focusing on the increase of resource efficiency. The environmental assessment shows the ecological advantages of the developed concept compared to conventional concrete elements and underlines the potential for further developments. Assessment of structural wood-based wood lightweight concrete composites are illustrated in this paper.

Hybrid cross-laminated timber plates (HCLTP) - numerical optimisation modelling and experimental tests

I. Sustersic, B. Brank, B. Dujic, J. Brezocnik, I. Gavric, S. Aicher, G. Dill-Langer, W. Winter, A. Fadai, T. Demschner, G. Ledinek

This paper presents the development of two new types of hybrid cross-laminated timber plates (HCLTP) with an aim to improve structural performance of existing cross-laminated timber plates (Xlam or CLT). The first type are Xlam plates with glued timber ribs and the second type are Xlam plates with a concrete topping. A numerical optimisation was performed to study optimal plate setups in terms of ultimate limit state and serviceability limit state requirements. The numerical outcomes served as input for defining the specimens for experimental tests on subassemblies and full-scale specimens. The new elements in general show improved structural performance with less material used. Experimental and numerical investigations serve as essential information for further extensive parametric studies of hybrid cross-laminated timer plates and development of design models and principles for implementation in the building codes.

Long-term testing of timber-steel hybrid beams

F. Riola Parada, W. Winter, K. Tavoussi

Timber-steel hybrid beams have been proposed, tested and analyzed for their use in multi-storey buildings. It is expected that the use of steel will help to counteract the creeping behaviour of timber. A specific long-term test for timber-steel hybrid beams was designed and carried out during one year in order to verify this and other hypothesis. The hybrid beams were designed with an equivalent bending stiffness for the timber and steel components. The results were successful and showed that the hybrid performance can reduce, for this case of bending stiffness balance and after one year, the creeping values in approximately 50%, compared to the comparison pure timber beams.

Bracing ability of traditional wooden floors in Viennese buildings from the period of promoterism in case of earthquake

D. Stefanoudakis, A. Fadai, W. Winter

Historical buildings from the period of promoterism (“the Founder Epoch”) constructed between 1850 and 1910, so called “Gründerzeitgebäude” or “Wilhelminian style buildings” represent the main part of the building stock in Vienna. The bracing ability of traditional wooden floors in Viennese buildings have been tested in laboratory and field tests. The results were implemented in finite element 3D models and have been verified by analytical methods using simple models, mainly simple cantilever and beam models. The comparative calculations have shown that these wooden floors have a significant influence to the bracing ability of the traditional buildings in case of earthquake. This paper also demonstrates how the bearing capacity reserve can be improved.

Semi-rigid joints of timber-steel hybrid beams for multi-storey buildings

K. Tavoussi, W. Winter, A. Bradley, F. Riola Parada

Timber-steel hybrid beams have been proposed, tested and analysed for their use in multi-storey buildings. Based on successful single span tests, which were presented in previous WCTEs and in the current WCTE 2016, a proposal is made to design semi-rigid joints in order to achieve the objective of timber-based multi-storey frame constructions. The concept of the connection is presented and the quite promising results are shown, which can be seen as a solid basis for the further development of this system.

Timber-glass composite: long-term behavior

A. Fadai, F. Nicklisch, M. Rinnhofer

Up to now, structural sealant glazing façades have been extensively applied. They are at the cutting edge of technology and meet the highest standards. The objective of several research projects was to develop stiffening glass fronts, which replace expensive frameworks or wind bracings behind the large glass windows. Thus, potential applications of timber-glass composites (TGC) as alternative stiffening constructions for multi-story façades were investigated. Based on the results of those previous research projects the Department of Structural Design and Timber Engineering (ITI) coordinated the follow-up international research project “Load bearing timber-glass composites (LBTGC)” within the framework WoodWisdom-Net. In consideration of long-term behavior and practical application, the objective of the joint research project LBTGC was to develop load-bearing and stiffening TGC structures. With the purpose to meet the highest standards of cost effectiveness and environmental compatibility, alternative stiffening TGC constructions for multi-story facades were investigated. This paper illustrates these developments and application of TGC multi-story façades.

Wood-based multi-story buildings and fires in social contexts in Japan and Austria – comprehensive discussions on risk management

A. Tani, I. Mach

Sustainability and combustibility are both sides of utilization of wood. Wood is socially expected to be used in urban contexts because of the sustainability; nevertheless individual building owners have to pay additional costs for fire proof of buildings due to the combustibility of the material. Fire risks correlate to certain risk factors. The distribution of risk factors is influenced by various social conditions. Each risk factor causes distinctive fire risks, which have a certain tendency on the proportion between frequency and damages. Effective social and individual countermeasures against fires are decided by degree of frequency fire risks. This paper treats the structure of risk managements from the viewpoint of the characters of risk factors (individual issues) and the distributions of factors (social issues) in case we use wood in urban contexts as a comparative study between Japan and Austria based on statistical analysis.

Paris / Aqualagon-Village Nature / complex wood structural design

J.-M. Weill

C&E ingenierie, France

This document covers the analysis of the wood-steel accessible roof structure of the air pavilion and particularly the presentation of the assumptions adopted for the roof design. As a general view the uniqueness of this so-called large span structure is not to be a form-finding analysis with the very typical idea to find the best ratio between the volume of material and the span. At the contrary the shape of the surface is simply a consequence of its accessibility as a “promenade”. This situation has led to a very unusual level of complexity regarding the engineering design also maximize by the use of a non-isotropic material such as wood

Paris / restructurations / hybrid structures / the Halle Pajol project / Francoise Helene Jourda and Raphaelle Laure Perraudin Architects

J.-M. Weill

C&E INGENIERIE, France

Up to the Second World War, the materials selected and building methods used for traditional constructions were de facto, based on descriptive specifications representing standard solutions. Since the Second World War, the wide range of products and techniques available has led to the description of a standard solution being replaced by a liability to perform applicable to the building. In other words, do the technologies used for a project open up new possibilities in terms of the general organisational structures used for production purposes, generating hybrid systems by default? That is the initial statement of the Halle Pajol project designed in Paris by the Architects Françoise Hélène Jourda and her associate Raphaelle Laure Perraudin. This project is a remarkable example in which designing architectural technical solutions are: a process, leading to a new model (knowledge, innovation); and the combination of two systems or two forces (distribution of new technics and adaptation to local context), led by the customer, legislation, the design team and constructors.

The wooden parish church in Gallspach: topographical reference and tradition beyond materiality

E. Beneder, A. Fischer

The church in Gallspach (Upper Austria), a market town with 2800 inhabitants, was rebuilt. It is unusual in “village” surroundings to redefine not only a spiritual place but simply its “centre”. The striking form as much as the sympathetic impression of its execution as a wooden construction contributed decisively to the acceptance of this major transformation of one of the residents’ familiar places that is so important to the village identity. The extreme topographical location, however, provides no formal, typological or “stylistic” model for the new church. It is the specific place as such that requires its essence from the new building: its pathways, its spaces, its centre.