The Experts below are selected from a list of 72 Experts worldwide ranked by ideXlab platform

Dundu M. - One of the best experts on this subject based on the ideXlab platform.

  • Gusseted rafter-to-column connections of double-bay single channel portal frames
    2016
    Co-Authors: Tshuma B., Dundu M.
    Abstract:

    Abstract: Double-bay portal frames have several advantages over two single portal frames positioned adjacent to each other, however the connecting system can be a challenge, especially if the portal frame is formed from single cold-formed channels. The portal frames described in this paper consists of a column and two rafter members, formed from single cold-formed channels sections, and bolted back-to-back at the eaves joint through a gusset plate. Tests were performed to evaluate the structural performance of the eaves region of double-bay portal frames. The eaves region represents the distance from the point of maximum moment (eaves joint) to the point of zero moment (Contraflexure) in the rafters and columns respectively. The structures failed by local buckling in the compression flange and web of the rafters, outside the joints. The moment- curvature graphs proved that plasticity could not be achieved in these connections

  • Eaves connections of double-bay portal frames with staggered single channel cold-formed rafters
    2016
    Co-Authors: Tshuma B., Dundu M.
    Abstract:

    Abstract: Experimental tests were performed to evaluate the structural performance of the eaves region of double-bay portal frames with staggered cold-formed rafters. This region represents the distance from the point of maximum moment at the eaves joint to the point of zero moment (Contraflexure) in the rafters and columns respectively. The column and two rafter members are formed from single cold-formed channel sections, which are bolted back-to-back at the eaves joint. In order to simplify the connections the rafters are connected directly to the back of the web of the column at different levels. Particular attention was focused on the failure modes of the structures, the strength (resistance to moment) of the connection, the momentcurvature performance and the connection’s ability to form plastic hinges. In all the tested structures, the column failed by local buckling in the compression flange and web, between the upper and lower rafters. The moment-curvature graphs proved that plasticity could not be achieved in these connections

T Koyama - One of the best experts on this subject based on the ideXlab platform.

  • seismic behavior of circular fly ash concrete columns reinforced with low bond high strength steel rebar
    Structures, 2020
    Co-Authors: Junhua Wang, Y P Sun, T Takeuchi, T Koyama
    Abstract:

    Abstract This paper proposes the use of concrete with a high water/cement ratio of 0.65, 455 kg/m3 of mixed fly ash and low-bond high-strength (LBHS) rebar to develop resilient circular columns confined by bolted steel tubes. The test results indicated that the proposed bolted steel tube-confined fly ash concrete columns with LBHS rebar had great self-centering (SC) capacity and stable lateral load resistance until reaching a large drift value. Low bonds resulted in delayed yielding of the longitudinal rebar; therefore, the column had better deformability and durable SC capacity compared with a column with normal high-bond steel rebar. Furthermore, the anchorage tie plate at the Contraflexure section of double curvature columns was necessary to prevent the steel rebar from slipping. Shortening the anchorage length of the longitudinal rebar within the beam-column joint had little influence on the seismic behavior of the test column. Bolted steel tubes could provide better safety for testing columns compared with that of welded steel tubes, especially at the large deformation stage. The proposed OpenSees model can evaluate the seismic behavior of the test columns with good agreement. The lateral behavior of the test columns can be reasonably predicted by using an equivalent stress block and calculation method considering steel bond slip. The literature indicated that the combination of LBHS rebar and fly ash concrete as well as bolted steel tubes is a good alternative for the development of SC RC columns.

Tshuma B. - One of the best experts on this subject based on the ideXlab platform.

  • Gusseted rafter-to-column connections of double-bay single channel portal frames
    2016
    Co-Authors: Tshuma B., Dundu M.
    Abstract:

    Abstract: Double-bay portal frames have several advantages over two single portal frames positioned adjacent to each other, however the connecting system can be a challenge, especially if the portal frame is formed from single cold-formed channels. The portal frames described in this paper consists of a column and two rafter members, formed from single cold-formed channels sections, and bolted back-to-back at the eaves joint through a gusset plate. Tests were performed to evaluate the structural performance of the eaves region of double-bay portal frames. The eaves region represents the distance from the point of maximum moment (eaves joint) to the point of zero moment (Contraflexure) in the rafters and columns respectively. The structures failed by local buckling in the compression flange and web of the rafters, outside the joints. The moment- curvature graphs proved that plasticity could not be achieved in these connections

  • Eaves connections of double-bay portal frames with staggered single channel cold-formed rafters
    2016
    Co-Authors: Tshuma B., Dundu M.
    Abstract:

    Abstract: Experimental tests were performed to evaluate the structural performance of the eaves region of double-bay portal frames with staggered cold-formed rafters. This region represents the distance from the point of maximum moment at the eaves joint to the point of zero moment (Contraflexure) in the rafters and columns respectively. The column and two rafter members are formed from single cold-formed channel sections, which are bolted back-to-back at the eaves joint. In order to simplify the connections the rafters are connected directly to the back of the web of the column at different levels. Particular attention was focused on the failure modes of the structures, the strength (resistance to moment) of the connection, the momentcurvature performance and the connection’s ability to form plastic hinges. In all the tested structures, the column failed by local buckling in the compression flange and web, between the upper and lower rafters. The moment-curvature graphs proved that plasticity could not be achieved in these connections

Tshuma Brighton - One of the best experts on this subject based on the ideXlab platform.

  • Eaves connections of double-bay portal frames
    2015
    Co-Authors: Tshuma Brighton
    Abstract:

    Abstract: Tests to determine the structural capacity, failure modes and the economy of the eaves region of double-bay portal frames made from cold-formed lipped channels connected back to back at the eaves joint are presented. Two double-bay portal frame eaves joint configurations, namely; Eaves Connection Type 1 (ECT-1) and Eaves Connection Type 2 (ECT-2) are investigated. In ECT-1, two rafters are connected to the column back-to-back with one rafter connected to the column at a lower level than the other while, in ECT-2, two rafters are connected to the column at the same level through a hot-rolled steel gusset plate. Variables in the frames include the width of the channel flanges, strength of the channels, number of bolts, and thickness of the hot-rolled gusset plate. The joints are subjected to equal loads applied through pins at points of Contraflexure until failure. Failure modes and experimental results are observed, recorded and analysed. A comparison between theoretical and experimental results is drawn up and analysed. In all the tested structures (ECT-1 and ECT-2), the cold-formed channels failed but the joints did not fail. Local buckling in the compression zone of the web and flange of the channels, bolt-bearing deformations and lateral deflection of gusset plates (in ECT-2 only) are the three modes of failure which were observed. Local buckling in the compression zone of the web and flange of the channels was the initial and ultimate failure mode in all structures. The moment-curvature graphs show that plasticity could not be achieved in both connections (ECT-1 and ECT-2). The unfactored resistances of the channels are not achieved by all the joints because of local buckling and bolt-bearing deformation failure. Both theoretical and experimental results show that the two investigated joints are semi-rigid and partial-strength joints since they possess some degree of rotational stiffness and moment capacity, but are insufficiently stiff to develop full continuity and unable to achieve full moment capacity of the connected members at the eaves joint. Furthermore, the investigation shows that ECT-1 is the most economic joint from a structural and material cost point of view, compared to ECT-2 joints. However, ECT-2 joints are...M.Phil. (Civil Engineering

A. Muttoni - One of the best experts on this subject based on the ideXlab platform.

  • PARAMETRIC ANALYSIS ON PUNCHING SHEAR RESISTANCE OF REINFORCED CONCRETE CONTINUOUS SLABS
    2019
    Co-Authors: Belletti Beatrice, A. Muttoni, Ravasini Simone, Vecchi Francesca
    Abstract:

    Punching shear resistance formulations provided by codes are usually calibrated on tests results of isolated specimens that typically simulate the slab zone within the points of Contraflexure around the column (hogging area). However, the behaviour of actual continuous flat slabs can be different than that of isolated specimens due to the beneficial contributions of moment redistributions and membrane actions that cannot take place in isolated specimens. This paper presents a parametric study carried out to highlight the influence of the main geometrical features and the reinforcement layout affecting the punching shear resistance of continuous slab

  • Shell Modelling Strategies for the Assessment of Punching Shear Resistance of Continuous Slabs
    Lecture Notes in Civil Engineering, 2018
    Co-Authors: Beatrice Belletti, R. Cantone, A. Muttoni
    Abstract:

    The punching shear resistance formulation provided by Model Code 2010 is calibrated on the basis of experimental tests on isolated slabs supported on columns. According to Level of Approximation approach, several quantities are required for the design punching shear resistance assessment, like the resisting moment and the radius of the line of moment Contraflexure. In this paper specific formulations are provided to adjust these quantities in order to take into account for moment redistribution and compressive membrane action effects. The punching shear resistance, mostly investigated for axisymmetric cases, in terms of loading and boundary conditions, will be analysed referring to actual rectangular RC continuous floors with orthogonal reinforcement layouts, largely adopted in practice. The results of nonlinear finite element analyses, carried out using PARC_CL crack model, are post-processed according to the Critical Shear Crack Theory to predict the punching shear strength of the continuous slab.

  • punching shear capacity of continuous slabs
    Aci Structural Journal, 2016
    Co-Authors: Jürgen Einpaul, Carlos E Ospina, Miguel Fernandez Ruiz, A. Muttoni
    Abstract:

    Provisions for punching shear design of reinforced concrete slabs are usually calibrated on the basis of results from tests on isolated specimens that simulate the slab zone within the points of Contraflexure around a column. However, the punching behavior of interior slab-column connections in actual continuous slabs without transverse reinforcement may be influenced by the effects of moment redistribution and compressive membrane action, which can lead to higher punching strengths and lower deformation capacities compared to those in isolated specimens. This paper discusses these behavioral differences on the basis of experiments performed on symmetric edge-restrained slabs and investigates available test data by means of a numerical model. A simplified calculation method (based on the Critical Shear Crack Theory) that accounts for these effects is also proposed. The calculation model shows consistent agreement with the results of the numerical evaluation and is sufficiently simple to be used in design and assessment.