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  • 1.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Reduction of Early Age Crack Risks in Concrete Walls by Using a New Casting Technique2016In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 26, no 3, p. 216-224Article in journal (Refereed)
    Abstract [en]

    Volumetric changes in early age concrete that are restrained might lead to cracks. The degree of restraint is influenced by the casting sequence and the dimensions of the castings. In the current study a new casting technique is proposed to reduce restraint in the newly cast concrete with a new arrangement of the structural joint to the existing old concrete. The proposed technique is valid for the typical structure wall-on-slab using one structural joint. This casting method means that lower part of the wall is cast together with the slab, and that part is called a kicker. Hereby, the behavior of the structure changes from a typical case wall-on-slab to a typical case wall-on-wall. It has been proven by the beam theory and demonstrated by numerical calculations that there is a clear reduction in the restraint from the slab to the wall using kickers. In the paper different kicker heights are studied with the aim of determining the minimum restraint in the upper part of the wall cast in contact with the kicker. The technique using kickers is compared with common measures used in the field to avoid cracking, such as cooling pipes in the new casting and/or heating cables in the adjoining old concrete. The presented method is both cost and time effective, as it opens the possibility to use larger structural length of each casting sequence.

  • 2.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Using Artificial Neural Network to Predict the Restraint in Concrete Culvert at Early Age2015In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 25, no 3, p. 258-265Article in journal (Refereed)
    Abstract [en]

    Estimation of restraint is very important for accurate prediction of the risk of concrete cracking at early age. The present study predicts the restraint in 324 walls and 972 roofs for a concrete culvert. A parametric study included the thickness and width of the roofs, thickness and height of the walls, thickness and width of the slab, and length of the structures. Each parameter increased or decreased the restraint in the walls and the roofs. The calculation of the restraint was done elastically by the finite-element method (FE). The results were used by an artificial neural network (ANN) tool, where firstly an influential percentage was investigated as input parameters on the restraint prediction. Equations have been derived by the ANN model to calculate the restraint in the walls and the roofs. It was then used in an Excel sheet to calculate the restraint and compare the result with the result from the finite-element calculations giving high accuracy between the ANN model and the FE calculations

  • 3.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Steel Concrete Composite Structures: Part II: Introduction2010In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 20, no 2, p. 126-126Article in journal (Refereed)
  • 4.
    Collin, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nakamura, Shunichi
    SEI Editorial Board.
    Steel Concrete Composite Structures: Introduction. Part I2009In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 19, no 4, p. 395-Article in journal (Other academic)
  • 5.
    Edskär, Ida
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Lidelöw, Helena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Wind-Induced Vibrations in Timber Buildings-Parameter Study of Cross-Laminated Timber Residential Structures2017In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 27, no 2, p. 205-216Article in journal (Refereed)
    Abstract [en]

    A current trend (2016) to construct high-rise timber buildings is seen. In order to understand the limitations posed by the timber material, wind-induced dynamic behaviour causing vibrations in the serviceability limit state has to be studied. The aim of this research is to calculate the natural frequency and acceleration levels of timber buildings having a cross-laminated timber structure to further the understanding of its behaviour and how a change in parameters affects building performance as reflected against comfort criteria. The results were calculated through finite element modelling using commercial software and by performing a modal analysis. The parameters under scrutiny were material stiffness, wall density, damping ratio, building height, and building footprint. The results show that even at moderate building heights (12-14 storeys), the comfort criteria are not fulfilled. Furthermore, the interaction between stiffness and mass for timber buildings needs to be explored further. And since the change of building footprint has a strong influence on the dynamic behaviour, the interplay between architectural and structural design becomes more important. Finally, more data on measurements of damping in timber buildings need to be collected to further validate simulation models.

  • 6.
    Frangi, Andrea
    et al.
    SEI Editorial Board.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Geier, Roman
    IABSE WC2.
    Bridges with Integral Abutments: introduction2011In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 21, no 2Article in journal (Other academic)
  • 7.
    Hällmark, Robert
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Swedish Transport Administration, Luleå, Sweden.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Ramböll, Luleå, Sweden.
    Post-Installed Shear Connectors: Monitoring a Bridge Strengthened with Coiled Spring Pins2019In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 29, no 2, p. 225-233Article in journal (Refereed)
    Abstract [en]

    Traffic density and vehicle weight have been increasing over time, which implies that many existing road bridges were not designed for the high service loads and increased number of load cycles that they are subjected to today. One way to increase the traffic load capacity of non-composite steel–concrete bridges is to post-install shear connectors. This paper presents a study of a steel–concrete bridge that has been strengthened with post-installed coiled spring pins, a type of connector which can be installed from below while the bridge is still in service. The strengthening method and design procedure are presented, along with the results from field monitoring performed to evaluate the behaviour of the strengthened structure. The results from the strengthened and non-strengthened sections show that the coiled spring pins counteract the slip and increases the degree of composite action. Finite-element models of the field tests were created in order to compare the results using different design assumptions and establish a suitable level of detail for modelling the shear connectors.

  • 8.
    Hällmark, Robert
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Möller, Mikael
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    The behaviour of a prefabricated composite bridge with dry deck joints2013In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 23, no 1, p. 47-54Article in journal (Refereed)
    Abstract [en]

    This paper describes the monitoring of a one-span composite bridge in northern Sweden. The bridge was built in 2000, with prefabricated deck elements connected to steel girders, and the back walls as well as the piers were also prefabricated. The monitoring was required to clarify the doubts regarding whether a bridge with dry deck joints can be expected to perform as a conventional composite bridge, with in situ cast deck and sections with sagging moments. To get a better understanding of the long-term structural behaviour, the bridge was monitored both during 2001 and 2011, instrumented with equipment measuring the deflections and strains in the steel cross section. The bridge was loaded with a truck in midspan having a total weight of 25 t. When the truck was centred between the girders, the results showed a symmetric behaviour, with respect to deflections and stresses. For the case with the truck stationed right above one of the steel girders, anti-symmetric behaviour was observed and studied by means of finite element calculations, taking into account the stiffness of the composite section as well as the end screens and the earth pressure below them.

  • 9. Hällmark, Robert
    et al.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Stoltz, A.
    Innovative prefabricated composite bridges2009In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 19, no 1, p. 69-79Article in journal (Refereed)
    Abstract [en]

    The competitiveness of composite bridges depends on different circumstances such as site conditions, local costs of material and staff, and the experience of the contractor. Two major advantages of composite bridges compared to concrete bridges are the ability of the steel girders to carry the weight of the formwork and the fresh concrete, and the shorter construction time which not only saves money for the contractor but even more for the road users. A further step is to prefabricate not only the steel girders, but also the concrete deck. In this paper, a new concept for composite bridges is described, with dry joints between the prefabricated concrete elements. The principal of the technique is presented, as well as some laboratory test simulating the load situation at an internal support in a multi-span bridge. Also, some experiences from an already built single span composite bridge with dry joints are presented.

  • 10.
    Koltsakis, Efthymios
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Noury, Pourya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Delft University of Technology.
    The Contact Problem of Roller Bearings: Investigation of Observed Failures2016In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 26, no 3, p. 207-215Article in journal (Refereed)
    Abstract [en]

    The present paper addresses how the commonly used Hertz formulas for contact stresses underestimate the actual stresses seen in practice due to temperature differentials, misalignments and other contruction-related defects. First, two failure cases of Swedish bridge roller bearings are analyzed and discussed; then, a detailed finite element (FE) model is used to investigate the accuracy of the traditional roller bearing design rules in view of issues such as abutment and girder deformability, misalignment imperfections and material nonlinearity. The bearing capacity of the studied rollers as provided by the manufacturer is used as reference. A rigorous FE model that accurately models girder, roller assembly and abutment provides the necessary information for the assessment of the related contact stresses, which were traditionally calculated by means of the Hertz analytical formulas. Numerical results first establish that roller bearings develop contact stress concentrations at the outer edges of the cylindrical drums. Second, it is established that the contact stresses are very sensitive to misalignment imperfections between the bridge girder and the abutment. Last, it is shown that the roller bearings develop inelastic deformation at relatively low loads in relation to the design load. These reasons, combined with the unlikelihood for roller bearings to shake-down, constitute the basis of the observed roller bearing failures.

  • 11.
    Pipinato, Alessio
    et al.
    AP& P srl, Rovigo, Italy.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Hällmark, Robert
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Prolonging the Lifetime of Old Steel and Steel–Concrete Bridges: Assessment Procedures and Retrofitting Interventions2019In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 29, no 4Article in journal (Refereed)
    Abstract [en]

    The structural analysis of existing bridges is not widely covered by the various codes and standards, resulting in the insecure and, in some cases, critical condition of this type of structure. Regarding national regulation, few states include compulsory codes that define the methods and procedures of inspection, assessment, maintenance and retrofitting of bridges. Although an accurate retrofitting procedure can prolong the life of an existing bridge, the more accurate management of national infrastructure assets can result in financial savings in the long term. This article deals with: (a) the assessment step-level procedure, (b) suggestions for bridge load tests and bridge categories, (c) bridge material analysis, (d) structural testing analysis, and (e) the main retrofitting interventions to prolong the life of existing steel and steel composite bridges. Furthermore, a representative case study is analysed and discussed, including examples of the retrofitting solutions implemented to prolong the service life of the bridge.

  • 12.
    Pétursson, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Andersson, Jörgen
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Monitoring of a swedish integral abutment bridge2011In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 21, no 2, p. 175-180Article in journal (Refereed)
    Abstract [en]

    One of the most commonly discussed problems regarding bridges with integral abutments is the influence of longitudinal elongation of the superstructure as a result of seasonal temperature variations. A bridge built with integral abutments is often supported by a row of piles made of steel or concrete. The longitudinal elongation of the superstructure induces a displacement and a rotation at the top of the pile, which in turn may cause strains that exceeds the yield strain. Such seasonal variations may lead to low-cyclic fatigue failure in the pile. Therefore, it is of great interest to investigate the amplitude of these strains, as well as the general behaviour of the bridge. In 2005, the European R&D project, INTAB (RFSR-CT-2005-00041, "Economic and Durable Design of Bridges with Integral Abutments, 2005-2008") was started. Within the INTAB project a composite bridge was built and monitored in Northern Sweden.

  • 13.
    Pétursson, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Möller, Mikael
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Low-cycle fatigue strength of steel piles under bending2013In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 23, no 3, p. 278-284Article in journal (Refereed)
    Abstract [en]

    Clamped abutment piles for integral abutment bridges experience both a compressive normal force and bending load cycles stemming from daily and yearly temperature variations. This paper describes experiments using full-scale models of clamped piles to demonstrate that a steel pipe pile can accommodate large inelastic deformations under strains six times greater than the yield strain for several hundred load cycles. This indicates that by permitting pile strains in excess of the yield strain (which is not permissible under most current design codes), integral abutment bridges could be erected with spans of up to 500 m and a projected service life of 120 years. The tests were carried out as a step towards the development of design rules for determining the capacity of piles for integral abutment bridges.

1 - 13 of 13
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