Robert JockwerChalmers University of Technology · Department of Architecture and Civil Engineering
Robert Jockwer
Dipl.-Ing. Dr. sc. ETH
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426
Citations
Citations since 2017
Publications
Publications (49)
This report is a publication of the European Network COST Action CA20139 “Holistic design of taller timber buildings – HELEN”, established with the aim to “work towards optimized holistic
approaches to improve the performance of taller timber buildings and to widen their competitiveness and use across the EU and rest of the world” (https://cahelen...
When producing a tender, contractors manually analyze client requirements contained within
many different text documents. The combination of requirements lead to crucial design decisions and
every decision is related to costs and risks. This study explores the possibility of making the client
requirement analysis in design-bid contracts automated t...
This paper provides a novel insight into using reversible mass timber connectors in light-timber framed (LTF) construction to create dismountable, panelised LTF construction systems that enable adaptable building design and panel reuse in the context of a circular economy. The study presented in this paper focused on Australian LTF panelised constr...
This paper describes results and analysis of experiment of compression behavior parallel to grain of glulam (Norway Spruce, Japanese cedar, and Japanese cypress), especially in damage zones near loading plates and joints. To investigate the influence factors of physical properties and the mechanism of the damage zone near the loading plates or the...
p>Project tendering is the construction business “Tightrope-walking.” It is a time-limited balance act where technical and business specialists find the best technical proposal at the right price. The purpose and aim of this study were to explore artificial intelligence (AI) in the tender work and to identify challenges and possibilities with data-...
This paper describes results and analysis of experimental testing of entire and partial compression strength and stiffness parallel to the grain of solid timber (Japanese cedar). To investigate the spreading effects, the size effect of strength and stiffness, and the mechanism of the damage zone located close to the loading plates, tests on 90 spec...
This paper discusses the design principles of timber connections for ductility with focus on laterally-loaded dowel-type fasteners. Timber connections are critical components of timber structures: not only do they join members, but they also affect load capacity, stiffness, and ductility of the overall system. Moreover, due to the brittle failure b...
Connections made with laterally loaded dowel-type fasteners are important details in timber structures. According to Eurocode 5, their load-carrying capacity can be calculated with the so-called European Yield Model (EYM) and simplified rules for the determination of slip-moduli are given. The slip modulus is given as a mean value for the serviceab...
Knowledge on the short and long term deformation behavior of highly loaded components in tall timber buildings is important in view of improving future design possibilities with respect to serviceability, both in the construction and in the operational state. In this paper, we present the results of a monitoring case-study on a tall timber-hybrid b...
Glued-in rods are important connecting and reinforcing elements in modern timber engineering used in new and existing timber structures. The complex stress distribution along the bondline between rod and wood depends on the type and properties of the adhesive and the type of load application. In this chapter, different models for the determination...
With the ever-increasing popularity of engineered wood products, larger and more complex structures made of timber have been built, such as new tall timber buildings of unprecedented height. Designing for structural robustness in tall timber buildings is still not well understood due the complex properties of timber and the difficulty in testing la...
![Figure 1: Overview of consequences, modified from JCSS (2008) [20] and...](profile/Joachim-Schmid-4/publication/348389940/figure/fig1/AS:978780659146754@1610370902227/Overview-of-consequences-modified-from-JCSS-2008-20-and-Schubert-2009-21_Q320.jpg)
With the increasing number of complex and tall timber buildings with a significant share of unprotected timber surfaces, questions arise about the contribution of the combustible structural elements to the fire development (fire dynamics) as well as on the robustness of these buildings. In recent building projects, measures for robustness have been...
The paper reviews the recent development of design code and the industrial practices of timber structure in Europe as a referece for the development of the Japanese timber industry.
The construction sector has a significant share of Green House Gas emission and raw material consumption globally. Among common construction materials, timber has a long tradition of numerous applications as a renewable material. The implementation of the concept of circularity in the process of the construction of timber buildings has a high poten...
Final report about the investigations and development of deign methods of connections in beech hardwood
A more holistic way to look at structural robustness is presented in this paper, using a multi-scale approach. Please contact me for more information.
Content of the paper:
• Overview of robustness-related provisions in the Eurocodes and other relevant standards
• Discussion of the requirements and design methods to design for robustness
• Presentation of the proposed approach for robustness for the 2nd-generation EN 1995-1-1 Eurocode 5
Dowel-type connections in timber structures should be typically designed in a way that, if the load bearing capacity is exceeded, desirable ductile failure should likely occur, i.e. yielding of the metal dowel or embedment of the timber. However, the probability of brittle failures cannot be completely avoided in many cases. If the connection is lo...
Conceptual and environmental challenges, coupled with a heightened systemic and contextual awareness in architectural research and design, have initiated new ways of thinking about wood and wooden architecture, shifting the focus on adaptability, scalability, and material efficiency. This book brings together a collection of recently built examples...
Connections with metal dowel-type fasteners are important details in timber construction, connecting single members and elements to larger structures. The load-carrying capacity can be described by different failure modes of the fasteners and in the surrounding timber. These failure modes show a dependency on different dimensions and material prope...
Connections in timber beams loaded perpendicular to grain are prone to brittle failure due to fracture induced by tension perpendicular to grain stresses in the surrounding timber. Different approaches can be found in literature and design codes to account for the reduction of load-carrying capacity in the design of the structure. In this study sel...
Standards and design codes are necessary to guarantee the desired safety and performance of structures. With regard to timber structures, considerable differences exist in the standards and design codes between Europe and Japan. In this contribution the framework of standards and design codes in Europe and Japan is explained and compared. As an exa...
The mechanical behaviour of timber-to-timber connections with an internal panel and dowels of bamboo composites were experimentally assessed and a design method developed. Embedment tests on bamboo composite plates with different numbers of cross layers and shear/bending tests on bamboo composite dowels were performed, followed by full-scale tests...
In this paper, a closed form analytical solution for glued-in-rod (GiR) joints is derived by solving the governing differential equations and accurately applying the boundary conditions in a cylindrical coordinate system for a GiR joint comprising of a rod, adhesive (glue) and timber. The results of the analytical model are compared with 3D continu...
Significant technical advances and developments in the field of timber
connections within the last years have fostered the recent renaissance of timber
as a structural material. An increased range of connection types and corresponding
applications gives designers both opportunity and challenge. The result
is a noticeable trend towards systemized so...
![Crack in a beam with h=100mm\documentclass[12pt]{minimal}...](publication/313833501/figure/fig2/AS:960009219350585@1605895442961/Crack-in-a-beam-with-h100mmdocumentclass12ptminimal-usepackageamsmath_Q320.jpg)
The load bearing capacity of glued laminated timber beams is size dependent. A material based size effect occurs due to the natural variability of the timber properties and can be explained with the Weibull weakest link theory. The Weibull type size effect has received much attention in the timber research community in the past as it is the dominat...
Fracture propagating along the grain of timber is one of the most relevant failure mechanisms due to the wood’s low strength and its brittle failure behaviour when subjected to excessive shear and tensile stresses perpendicular to the grain. According to the current procedures, the fracture energy of wood is determined on small clear specimens. How...
Norway spruce glulam beams with artificial horizontal slits of different length and depth were reinforced using self-tapping screws and threaded steel rods in order to restore their load-carrying capacity and stiffness. The study aimed at evaluating the effects of strength and stiffness of the applied reinforcing elements on the load-carrying capac...
Impressive large span constructions are more
often realized in timber or engineered wood
products over the past years. For example,
glulam beams provide the possibility for the
use of timber in halls, bridges and multi storey
buildings. The limitation in span of solid timber
members was lifted due to glulam production.
But the environmental conditi...
Two-part, cold-cure epoxy adhesives are most suitable for on-site bonding. Careful surface preparation is essential. Design approaches for flexural and shear strengthening of timber beams are presented. Practical guidelines for on-site bonding are given. Approaches to bondline delamination modeling is described. a b s t r a c t Timber engineering h...
The reinforcement of new and existing timber structures has been the subject of considerable research
and development in recent years. New materials and methods for reinforcement have been developed
and used in practise. However there is currently a lack of harmonised european standards governing
this field. In this paper the current three step pyr...
The structural behaviour and failure mechanisms of unreinforced and reinforced notched glulam beams were studied in a test series. It could be shown that shear failure of the reinforced notched beam is an important failure mechanism and that adequate reinforcement in tension perpendicular to grain and shear is required in order to regain the load-c...
In this paper different design approaches for connections loaded perpendicular to the grain are evaluated with regard to their reliability. The structural behaviour of connections loaded perpendicular to the grain is described based on existing experimental and theoretical studies. The detailed failure behaviour of dowel connections loaded perpendi...
The impact of knots and grain deviations on the perpendicular to grain strength of wood was studied by computational models and test results from literature. It was found that knots in general seem to have a positive influence on the perpendicular to grain fracture strength. A strongest link model for strength analysis relating to failure due crack...
In order to benefit from the advantages of fully threaded self-tapping screws as reinforcing elements, it is essential to have detailed knowledge about the strength and stiffness of screws with different shank to grain angles subjected to combined axial and lateral loading. In this paper a design model is proposed for the calculation of the load-ca...
Notches are details that significantly reduce the load-carrying capacity of beams made of timber. The amount of reduction was the subject of investigation in numerous studies from an experimental or theoretical point of view. The singular stress distribution around the notch corner can be described by equations based on linear elastic fracture mech...
The load carrying capacity of glued laminated timber beams is reduced considerably by notches at the support on the tension side of the beam. Stress concentrations at the notch corner together with low shear and perpendicular to the grain tensile strength may lead to brittle failure. For the prediction of the load carrying capacity of notched beams...
![Table 7 : Values of notch strength A' [Nmm -3/2 ] for glulam from...](profile/Rene-Steiger/publication/278672372/figure/tbl3/AS:669369872969744@1536601622665/Values-of-notch-strength-A-Nmm-3-2-for-glulam-from-experimental-results-A-mean_Q320.jpg)
For structural use solid timber has to be strength graded. In order to stay economic, the grading process usually focuses on the most important physical and mechanical properties: density, bending strength (MOR) and modulus of elasticity (MOE). Grading standards also state how further mechanical properties can be derived from these basic property v...
Projects
Projects (6)
The main objective of the proposed TC is to develop standardized and reliable procedures for characterizing the resistance,
stiffness and deformation properties of timber joints that are appropriate for design provisions and guidelines. Two types of
fasteners and loading will be addressed: i) axially loaded self-tapping screws (STS) under axial and lateral loads and ii) laterally
loaded dowel-type fasteners, under both quasi-static and cyclic loading.
The purpose of the study is to investigate the possibilities of combining production knowledge and design knowledge in early stages of the construction process with the use of artificial intelligence. The increased digitalization in the constructions industry opens up possibilities for data-driven decisions in the tendering and conceptual design phase, both in terms of optimizing work methods as wells as reducing risks.
The aim of this research project is to study the role of assessment on the reliability analysis of existing structures. The project focuses on existing masonry and timber structures to evaluate the benefits of assessment with regard to the economy and safety of structures.
