Journal articles
Author(s) | Title | Journal | Issue | Page | Category |
---|---|---|---|---|---|
Abdellahi, Majid; Heidari, Javad; Bahmanpour, Maryam | A new predictive model for the bond strength of FRP-to-concrete composite joints | Structural Concrete | 4/2014 | 509-521 | Technical Papers |
AbstractIn this work, gene expression programming (GEP), as a new tool, has been used to predict the bond strength of fibre-reinforced polymer-to-concrete composite joints as the performance symbol of this structure. Some 238 datasets were collected from the literature, divided into 192 and 46 sets at random and then trained and tested respectively by means of GEP. The parameters width of prism, concrete cylinder compressive strength, width of fibre-reinforced polymer (FRP), thickness of FRP, modulus of elasticity of FRP and bond length were used as input parameters. Using these input parameters, the bond strength of FRP-to-concrete composite joints in different conditions was predicted in the GEP model. The training and testing results in the GEP model show that GEP is a powerful tool for predicting the bond strength values of the FRP-to-concrete composite joints in the range considered. x | |||||
Zhou, Xiaohai; Derome, Dominique; Carmeliet, Jan | A new procedure for selecting moisture reference years for hygrothermal simulations | Bauphysik | 6/2016 | 361-365 | Fachthemen |
AbstractHygrothermal models allow designers to evaluate the hygrothermal performance of building envelopes. However, hygrothermal modeling needs the input of the external climate loading, a moisture reference year, to evaluate moisture damage risk of building envelope. In this paper, a new procedure is proposed for selecting moisture reference years. A metric, called Climatic Index, combining wind-driven rain load and potential evaporation is developed in this study. Climatic Indices over 30 years are determined for a wall envelope located in Zurich, Switzerland. The hygrothermal performance of the wall envelope and its moisture damage risk are simulated and evaluated using a hygrothermal risk indicator, called the RHT Index. A clear correlation between Climatic Index and RHT Index is found for the specific moisture damage considered, mold growth. The selection procedure combines a first selection of three years around the 10 % level criterion based on the Climatic Index, followed by a careful comparison of different years based on RHT Index and a final selection of the year with the largest RHT Index as moisture reference year. The combination of Climatic Index and RHT Index allows for the selection of moisture reference years with known level of damage risk. x | |||||
Thieken, Klaus; Achmus, Martin; Lemke, Katrin | A new static p-y approach for piles with arbitrary dimensions in sand | geotechnik | 4/2015 | 267-288 | Fachthemen |
AbstractWhen it comes to the general design of laterally loaded piles in offshore environments, bedding resistance is usually modelled by the p-y method recommended in the offshore guidelines (OGL). Several investigations presented in the literature indicate that the head displacements of large-diameter monopiles are underestimated for extreme loads but overestimated for small operational loads. An extensive evaluation of the OGL method is presented here using three-dimensional numerical simulations. The evaluation has shown that the OGL method is not applicable for the design of large-diameter piles. Moreover, modified p-y formulations presented in the literature accounting for the effect of the pile diameter are also not generally suitable for piles with arbitrary dimensions and load levels. Therefore, the derivation of a new p-y approach is presented in detail. The new approach consists of “basic p-y curves” that are valid for a pile of infinite length exhibiting a constant horizontal deflection. In an iterative scheme, these basic curves are adapted depending on the pile deflection line and the pile length to account for a more realistic bedding resistance along the pile shaft. A comprehensive parametric study with 250 pile-soil systems reveals that the new p-y approach is able to predict the horizontal loadbearing behaviour as well as the local pile-soil interaction quite realistically. x | |||||
Braham, M.; Ruggerini, A.; Ubertini, F. | A numerical model for roof detailing of cold-formed purlin-sheeting systems | Stahlbau | 4/2008 | 238-246 | Fachthemen |
AbstractVarious methods are suggested in the available codes to design roof detailing in cold formed screwed-down roof systems made of cold-formed purlins covered with metal sheeting. The evaluation of the global anchorage force of the roof and the local forces in fasteners is pursued aiming at designing support detailing and purlin-sheeting connection, respectively. Two factors, “R” and “r”, are here employed to synthetically describe the stabilization forces that are required at the supports and along the span. It is shown that these two factors are implicitly provided by some codes for steel structures, but they can be even directly calculated by a simplified finite element model of the whole roof system, here presented. A comparison with the other available approaches is carried out, revealing that the proposed model is an extremely useful tool both for the design and the verification of the structural elements. The described procedure for calculation is shown to be extremely general and easily adaptable to new roof systems, with structural details even not foreseen in the actual codes. For example it can be used to solve the lack of Eurocode 3, Part 1-3, Chapter 10, because, as opposed to the assumption of Eurocode, elastic lateral support can here be envisaged, instead of full lateral support. x | |||||
Nagel, F.; Stascheit, J.; Meschke, G. | A Numerical Simulation Model for Shield Tunnelling with Compressed Air Support | Geomechanik und Tunnelbau | 3/2008 | 222-228 | Fachthemen |
AbstractThis paper is concerned with a numerical simulation model (ekate) specifically designed for shield tunnelling in fully and partially saturated soils based upon the Finite Element Method (FEM). The model considers all relevant components - the soil, the lining, the tail void grouting, the hydraulic jacks and different types of face support - involved in shield tunnelling. The surrounding soft soil is formulated as a three-phase material, consisting of the soil skeleton, pore water and air. This model allows for the simulation of consolidation processes in partially saturated soils as well as of flow of compressed air often used as temporary face support during repair interventions at the cutting wheel. Despite the complexity connected with the relatively high degree of realism of the simulation model, only little effort is required from the user to establish a realistic 3D model for shield tunnelling. To this end an automatic model generator has been developed which allows for a user friendly generation of the discretized model including all components involved and to investigate variants with a minimum effort for the user. The model allows for realistic predictions of settlements and also provides information on deformations and stresses in the ground, the lining and the TBM, respectively. In addition to its use as a prognosis tool in the design process, in particular for tunnelling projects in sensitive urban areas, the model also may be used to assist the driving and steering process in mechanized tunnelling. The paper provides an overview over the main components of the model, the automatic model generator and the tri-phasic representation of the soil. A simulation of a compressed air intervention of a shield tunnel in soft soil demonstrates the applicability of the model. x | |||||
A Particle of Clay. The Biography of Alec Skempton, Civil Engineer (Niechcial, J.) | Bautechnik | 11/2003 | 854-855 | Bücher | |
Silva, Ricardo; Faria, Duarte M. Viúla; Ramos, A. Pinho; Inácio, Micael | A physical approach for considering how anchorage head size influences the punching capacity of slabs strengthened with vertical steel bolts | Structural Concrete | 4/2013 | 389-400 | Technical Papers |
AbstractThe introduction of new vertical steel bolts is an easy, practical and common solution for retrofitting and strengthening slabs for punching. Although a common option where punching strengthening is concerned, few studies exist regarding how the bolt's anchorage dimensions and its embedment in the concrete slab affect the strengthening efficiency. This work presents an analytical approach that is able to predict the punching capacity of slabs strengthened with post-installed vertical steel bolts, taking into account the anchorage dimensions and positioning plus the material properties. This approach results from the combination of two physical models: one provided in the fib Model Code for Concrete Structures 2010 regarding the punching capacity estimation, and another that allows the deformation (crushing) of the concrete beneath the head of the anchorage to be taken into account. The predicted values are compared with experimental results, showing that the analytical approach is able to simulate correctly the anchorage behaviour and its influence regarding a slab's loadbearing capacity. A parametrical analysis is carried out in order to study the importance of different factors such as concrete compressive strength, longitudinal reinforcement ratio and steel bolt length, always accompanied by the effect of anchorage head size and embedment. x | |||||
Brameshuber, Wolfgang | A proposal for the restructuring of the Eurocode EN 1996-1-1 / Ein Vorschlag zur Neustrukturierung des Eurocode EN 1996-1-1 | Mauerwerk | 1/2015 | 52-63 | Fachthemen |
AbstractIn this article an attempt is made to simplify the application of EC 6 by a strict and clear division of the EC 6 into calculation, execution and materials. The calculation engineer does not, therefore, need to get involved with building materials specific parameters, which make it much more difficult to get a view over the variety of possible combinations. The introduction of classes in the characteristics that are relevant for building materials means that the structural engineer specifies suitable quantities necessary for his task, the builder/product manufacturer by suitable methods and choice of unit/mortar combinations achieves the required classes and, the product manufacturer, in particular, should be entitled to have the possibility of the individual specification, e. g. as part of general appraisal certificates. x | |||||
Kathage, Karsten; Lindner, Joachim; Misiek, Thomas; Schilling, Sivo | A proposal to adjust the design approach for the diaphragm action of shear panels according to Schardt and Strehl in line with European regulations | Steel Construction | 2/2013 | 107-116 | Articles |
AbstractIn Germany the stiffness and resistance of diaphragms used for stabilizing members are traditionally calculated according to the Schardt and Strehl approach. Compared with the approach of Bryan and Davies given in the ECCS Recommendations, it does not take into account the flexibility of the connections. This paper shows how to amend Schardt and Strehl’s approach to include this flexibility, leading to more realistic values of diaphragm stiffness. The article also introduces new procedures for the calculation of the resistance, adopted from European standards and recommendations. Finally, both a test and an example taken from the literature are recalculated for comparison. x | |||||
Baji, Hassan; Ronagh, Hamid R. | A reliability-based investigation into ductility measures of RC beams designed according to fib Model Code 2010 | Structural Concrete | 4/2015 | 546-557 | Technical Papers |
AbstractA reliability-based investigation into the ductility measures for reinforced concrete (RC) beams designed according to the current fib Model Code for Concrete Structures 2010 is presented in this paper. Based on the ductility ratio (= ratio of strain in tensile rebar to yield stress of steel), a limit state to ensure adequate ductility in RC beams is proposed. Results show that the ductility ratio generally follows a right-skewed distribution, and due to variability in the material properties and model error, there is high variability in the strain ductility. This high variability in the ductility ratio leads to a high probability of non-ductile behaviour for RC beam designs based on the code. This is more pronounced for normal-strength concrete and grade S500 steel. Based on a target probability taken from the literature, a modification to the allowable neutral axis depth advised by the code is proposed. The results presented in this paper indicate that more reliability-based studies of the safety factors provided by fib Model Code 2010 are needed in order to ensure adequate ductility in RC beams. x | |||||
A repairable connection for earthquake-resisting moment frames | Stahlbau | 1/2020 | 27 | Empfehlungen der Redaktion | |
Richards, Paul | A repairable connection for earthquake-resisting moment frames | Steel Construction | 3/2019 | 191-197 | Articles |
AbstractNominated for the Bernt Johansson Outstanding Paper Awards at Nordic Steel 2019 x | |||||
Längle, T.; Käppeli, L. | A road tunnel in difficult geology with cross-sections up to 300 m2 / Straßentunnel in schwieriger Geologie mit Querschnitten bis zu 300 m2 | Geomechanics and Tunnelling | 6/2010 | 727-738 | Topics |
AbstractThe 4.2 km Eyholz tunnel is part of the autobahn A9 and is the essential element in the bypass of Visp in the canton Valais, Switzerland. The tunnel passes through geologically problematic and also tectonically highly stressed zones (Rhone-Simplon fault). x | |||||
Patki, Mrunal A.; Mandal, Jnanendra Nath; Dewaikar, Dileep Moreshwar | A simple approach based on the limit equilibrium method for evaluating passive earth pressure coefficients | geotechnik | 2/2015 | 120-133 | Fachthemen |
AbstractA numerical method is developed for evaluating critical passive earth pressure coefficients Kp&ggr; for the case of an inclined rigid retaining wall resting against sloping cohesionless backfill. The methodology of the proposed investigation is based on the limit equilibrium approach with the assumption of a complete log spiral failure mechanism. The Kp&ggr; coefficients obtained from this study are compared with the existing theoretical and experimental results. The proposed Kp&ggr; values are on a par with the best upper bound solution given by Soubra and Macuh using the limit analysis method. Further, the results presented here compare fairly well with those given by Kerisel and Absi, which establishes the validity of the proposed research work. Efforts are taken to present the design tables for a wide variety of soil properties, soil-wall interface properties and geometrical properties of the wall and the backfill. x | |||||
Hamann, Thorben; Grabe, Jürgen | A simple dynamic approach for the numerical modelling of soil as a two-phase material | geotechnik | 3/2013 | 180-191 | Fachthemen |
AbstractIn many geotechnical problems, the presence of water and air in the voids of a soil skeleton has an influence on the behaviour of the soil. Effects such as time-dependent deformations, temporary reduction in the shear strength of the soil or even liquefaction of loosely layered sands can occur. To account for these effects in a geotechnical analysis, the soil has to be considered as a multiphase material with interaction between the single phases. A simple dynamic approach for the numerical modelling of a fully saturated soil with the finite element method using an explicit time integration rule is presented here. The governing equations describing the soil as a two-phase material are implemented within the framework of a user subroutine working as a constitutive model in the analysis. Simple problems considering different boundary conditions, static and dynamic loading conditions and non-linear material behaviour are investigated to verify the implemented approach. The results are compared with analytical solutions and with solutions obtained by the finite element method using an implicit equation solver. Compared with implicit integration methods, the approach presented has the advantage that - for dynamic analyses especially. An explicit integration method is often computationally more efficient for the analysis of large models with relatively short dynamic response times and for the analysis of extremely discontinuous processes such as dynamic pile driving. x | |||||
Schuss, M.; Pröglhöf, C.; Orehounig, K.; Mahdavi, A. | A simulation-powered approach to ventilation, lighting and shading systems control | Bauphysik | 6/2010 | 391-398 | Fachthemen |
AbstractThis paper reports on ongoing work toward implementing a predictive control approach for buildings systems for ventilation, lighting, and shading. The main objective of this method is the optimized control of multiple devices toward usage of passive cooling and natural lighting. In this way, control options (various opening positions of windows, shades, etc.) are generated and computationally assessed using a combination of option space navigation via genetic algorithms and numeric simulation. x | |||||
Yemez, K.; Altay, G. | A steel frame connection: I-beam to SHS column via bolted T-stub | Steel Construction | 3/2010 | 148-153 | Articles |
AbstractThis paper presents the outcome of an experimental study carried out by the authors on the performance of a connection between an I-beam and a square hollow section (SHS) column. In the light of practical and economic bolted field applications and transportation without damage by leaving the column exterior without projections, an appropriate joint type composed of T-stub connecting elements was studied. These connecting elements were bolted with long partially threaded studs passing through the SHS column. In order to observe the performance of the joint, four full-scale beam-column tee-joint specimens were tested under monotonic and cyclic loading in two groups. As a parameter, the rear face of the SHS column in the area of the connection was reinforced by backing plates in the second group of specimens. The results obtained are provided in terms of moment-rotation relationship and energy dissipation capacity. All specimens reached beam plastic load level at high deformation levels. Reinforcing the SHS column rear face with a backing plate resulted in an increase in strength and initial stiffness but a reduction in the energy dissipation capacity of the joint. Considering the overall cyclic performances, both joints maintained high plastic rotations in adequate resistance levels with acceptable energy dissipation capacities; consequently, they are suitable for use as semi-rigid partial strength joints in simply designed, braced steel frames in seismic regions or in unbraced steel frames in regions with less seismic activity. Additional component tests were carried out to understand better the component behaviour of the hollow section face in bending and to try to design component modelling parameters. The influence of bolt spacing and the distance between bolt rows on the resistance of the square hollow section face in bending was examined. As expected, when the bolts were closer to the sidewall, the resistance of the face increased. x | |||||
Heinisuo, Markku; Perttola, Henri; Ronni, Hilkka | A step towards the 3D component method for modelling beam-to-column joints | Steel Construction | 1/2014 | 8-13 | Articles |
AbstractThis paper deals with the component method for the structural design of steel joints in the 3D modelling of loads. The essential features of the method are presented in terms of the local and global analysis model. There is a discussion about the location of the local joint model, the definition of generalized joint displacements and the generic nature of the method. The proposed method is verified for a beam-to-column joint. Verification is carried out by a detailed 3D non-linear finite element analysis of a single joint. Other results in the literature are discussed briefly. One of the new components used in 3D modelling is introduced here. The proposed 3D component method seems to work rather well for moment resistances of joints in both ambient and fire conditions. Initial rotational stiffness needs to be studied more. Validation of the 3D component method is continuing with experiments on the end plate splice joints of rectangular tubular structures. x | |||||
Ramos, LuÃs F.; Lourenço, Paulo B.; Vermeltfoort, Ad. T.; Moreira, Susana | A students' challenge for the estimation of the maximum compressive load of masonry prisms / Studentenwettbewerb zur Ermittlung der maximalen Druckfestigkeit von Mauerwerksprismen | Mauerwerk | 5/2016 | 352-363 | Fachthemen |
AbstractThe paper presents the “IMC Students' Challenge” competition held in 2014, during the 9th International Masonry Conference, in Guimarães. The objective of the competition was to predict the maximum compressive load of two masonry prisms built of solid bricks, and of hollow blocks, with mortar joints. To increase the complexity of the problem, all prisms were tested under eccentric load. The students, who enthusiastically participated in the final laboratory tests, presented different approaches to estimate the maximum eccentric compressive force on masonry prisms. The challenge was a great experience, not only for students and conference participants, but also for sponsors and organizers. x | |||||
Chen, L.; Doerich, C.; Rotter, J. M. | A study of cylindrical shells under global bending in the elastic-plastic range | Steel Construction - Design and Research | 1/2008 | 59-65 | Articles |
Ishikawa, H.; Konno, H.; Mitamura, H. | A study of the new construction method for transverse box culverts by using the steel-concrete composite sandwich deck slab - cutting the cost of constructing expressways | Steel Construction | 3/2009 | 167-174 | Article |
AbstractExpressways are typically constructed on high embankments to accommodate transverse box culverts. If the embankment height could be reduced while still accommodating culverts, then the road construction costs could be lowered by reducing the required volume of embankment soil. The authors achieved this by devising a transverse box culvert whose steel-concrete composite sandwich deck slab resembles the composite slabs used for road bridges. x | |||||
Ozaki, Fuminobu | A study on a theoretical relationship between strain hardening of steel and plastic region length in a steel beam subjected to fire | Stahlbau | 9/2014 | 652-656 | Fachthemen |
AbstractThis paper presents a relationship between strain hardening of steel and plastic region length in a steel beam subjected to fire. A theoretical simple fire response analysis is proposed to investigate elasto-plastic behavior of the statically indeterminate heated beam. From observation of parametric calculations, it is clarified that large plastic region length in the beam, which is induced by the large strain hardening, is effective to avoiding strain concentration. This contributes to the robust attenuation of the thermal stress at the fire. x | |||||
Takenaka, H.; Kishida, H.; Nakai, H. | A Study on New Composite Girder using Prestessed Precast Concrete Slab by PPCS Method (Verbundträger mit vorgespannten, vorgefertigten Betonplatten - PPCS-Methode). | Stahlbau | 6/1986 | 165-174 | Fachthemen |
AbstractBerichtet wird über eine neue Idee für Verbundträger, kurz PPCS-Methode. Es werden die experimentellen Untersuchungen und numerischen Vergleichsrechnungen bei Einfeldträgern vorgestellt. Ferner wird auf die Verwendung der Methode bei Durchlaufträgern eingegangen und ihre praktische Anwendung bei einer Fußgängerbrücke gezeigt. Zum Konzept der PPCS-Methode:- Die einzelnen Betonfertigteilplatten werden auf die Stahlträger aufgelegt und die Fugen mit Epoxidharzkleber oder Zementmörtel vergossen. Nachträglich wird die Betonplatte dann mit in Hüllrohren liegenden Spanndrähten vorgespannt. - Die im Bereich der Schubdübel vorhandenen Löcher werden mit Zementmörtel verfüllt und somit der Verbund hergestellt. - Nach hergestelltem Verbund wird die Vorspannung reduziert und damit eine Zugkraft und ein negatives Biegemoment in den Verbundträger eingeleitet. x | |||||
Sjaarda, Matthew; Meystre, Thierry; Nussbaumer, Alain; Hirt, Manfred A. | A systematic approach to estimating traffic load effects on bridges using weigh-in-motion data | Stahlbau | 7/2020 | 585-598 | Aufsätze |
AbstractIn contrast to the Swiss load model used for new bridge structures (SIA 261), which has roots in a Europe-wide weigh-in-motion (WIM) study and considers the full design life of new structures, the model for existing structures (SIA 269) from 2005 is derived from load effects produced by traffic measured by country-specific WIM observations and considers a reduced return period. With growing concerns regarding the scarcity of resources, efforts should be made to ensure safety by increasing the knowledge of loads and load-carrying mechanisms, rather than through overdesign. This paper presents the methodology employed to use WIM data for generating maximum expected load effects on bridges and thus give engineers a tool with which bridge load effects can be accurately derived from real traffic. A re-evaluation using the methodology outlined here began this year. It is planned to use the results of this for the next revision of the Swiss National Annexes to the Eurocodes and SIA 269. x | |||||
Gamba, Francesco; Brino, Lorenzo; Triclot, Jacques; Hugot, Elsa; Barla, Giovanni; Martinotti, Giorgio | A TBM assembly cavern in the French Alps | Geomechanics and Tunnelling | 3/2017 | 256-264 | Topics |
AbstractThis paper deals with the cross-border section of the Lyon-Turin Line, i.e. the 57.5 km long Mont Cenis Base Tunnel between Saint Jean de Maurienne in France and the Susa valley in Italy. Works at Saint Martin La Porte started in 2015 including the 9 km TBM excavation along the south tube of the base tunnel between the access adits of Saint Martin La Porte and La Praz. In order to assemble the TBM, a large underground cavern has been excavated at the end of the Saint Martin La Porte access adit. The size of this cavern, with a length of approximately 45 m, a span of 23 m and a height of 22.2 m, and the geological and geomechanical conditions in the Carboniferous Formation at a depth of about 600 m made this work a challenge. The excavation and support methods adopted are described, together with the rock mass conditions and the observed ground behaviour. The monitoring data obtained during excavation are briefly presented, including the works schedule. x |