The Experts below are selected from a list of 384 Experts worldwide ranked by ideXlab platform

Schäfer Markus - One of the best experts on this subject based on the ideXlab platform.

  • Limitations of Plastic bending resistance for composite beams deviated from strain-limitation
    'Elsevier BV', 2021
    Co-Authors: Schäfer Markus, Zhang Qingjie, Braun Matthias, Banfi Mike
    Abstract:

    Due to the demand for sustainable constructions, composite structures have become more important and lead to slim and economic solutions with a low structural self-weight. EN 1994-1-1 distinguishes between four different cross-section classes for the determination of moment resistance. For the Plastic moment resistance, it is assumed, that each cross-sectional fibre can plastify without any limit on the strain. For standard composite beams with sagging moments and a high Plastic Neutral Axis, Plastic resistance and strain-limited resistance give similar results. For sections with a large compression zone height xpl and limited rotation capacity, concrete failure in the compression zone can occur before the Plastic moment resistance Mpl,Rd, is reached. The strain limit design becomes critical. This paper points out the impact of the concrete part on the design of composite beams. A parametric study comparing Plastic and strain limited moment resistance of a considerable variety of cross-sections has been carried out to develop the beam design methods considering compression zone height for the next generation of Eurocodes

  • Impact of reinforcement to moment resistance of composite slabs
    2019
    Co-Authors: Zhang Qingjie, Schäfer Markus, Kurz Wolfgang
    Abstract:

    Composite slabs lead to slim and economic structural solutions with a low selfweight. The determination of their moment resistance follows the regulations presented in EN 1994-1-1 (2004) which are based on Plastic design methods. The current version of Eurocode 4 does not consider explicitly additional reinforcement in the ribs for sagging moment resistance. However, the construction industry requires this possibility in order to provide economical and flexible design. Regarding this situation, further investigations are necessary to prove the applicability of Plastic design methods. In the case of high bottom reinforcement ratio, a deep position of the Plastic Neutral Axis occurs, and concrete compression failure may happen before most parts of the profiled steel sheeting and reinforcement yield. This leads to an overestimation of the bending resistance according to the Plastic design method. A parametric study, based on approximately 290.000 different combinations of various cross-section geometries and materials, is provided to compare the Plastic moment resistance with the resistance determined by strain-limited design. The results show that limitations are necessary to be enabled for the general application of Plastic design methods

  • Plastic DESIGN FOR COMPOSITE BEAMS - ARE THERE ANY LIMITS?
    2019
    Co-Authors: Schäfer Markus, Zhang Qingjie, Banfi Mike
    Abstract:

    Due to the demand for sustainable constructions, composite structures have become more important and lead to slim and economic solutions with a low structural self-weight. EN 1994-1-1 differentiate four different cross-section classes for the determination of moment resistance. For the Plastic design of the moment resistance it is assumed, that each cross-sectional fibre can plastify without any limitation of the strains. For standard composite beams in case of sagging moments and a high-lying Plastic Neutral Axis, Plastic design and strain-limited design give similar results. In the case of sections with a large compression zone height xpl and limited rotation capacity, a concrete failure in the compression zone can occur before the Plastic moment resistance Mpl,Rd, is reached. The strain limit design becomes decisive. This paper points out the impact of the concrete part on the design of composite beams. A parametric study comparing Plastic and strain limited moment resistance of a considerable variety of cross-sections has been carried out to develop the beam design methods considering high compression zone height of next generation of Eurocodes

  • Particularities for Plastic design of composite beams with deep Plastic Neutral Axis
    2018
    Co-Authors: Schäfer Markus, Zhang Qingjie
    Abstract:

    The demand for sustainable constructions increases the importance of composite structures as they lead to slim and economical solutions with a low self-weight of the structure. The determination of the moment resistance for composite beams follows the rules stated in EN 1994-1-1. Based on the slenderness c/t of the compressed parts of the steel-section, composite cross-sections are classified into four cross-section classes. This classification indirectly reflects the rotation capacity and susceptibility to local buckling. For class 1 and 2 cross-sections, the Plastic moment resistance of the crosssection may be considered. Otherwise, an elastic design (for class 3) or an elastic design considering local buckling effects (for class 4) is necessary. If the Plastic resistance of the cross-section is assumed, it is considered that each cross-section fibre may plastify without limitation of the strain values. For normal composite beams subjected to the sagging moments and with a high Plastic Neutral Axis, the real moment resistance is quite greater than one obtained by the method of the Plastic design. For sections with a large compression zone, xpl, a concrete failure in the compression zone can happen before the Plastic moment resistance of the composite cross-section, Mpl,Rd, is reached. Strain limit design, therefore, becomes critical. EN 1994-1-1 provides a limitation of the Plastic design resistance only for sections with steel grades S420 and S460. However, there is no guidance given for lower steel grades or the determination of the corresponding concrete compression force. This paper points out, that the rotation capacity of a composite section is dependent on the slenderness of steel crosssection parts and on the behaviour of the concrete part. A comparison of Plastic and strain limited moment resistances as well as the analysis of partial shear diagram-based strain limited design results in new findings for the limits of Plastic design methods

  • Limits of Plastic design for composite beams
    2017
    Co-Authors: Schäfer Markus
    Abstract:

    Due to the demand for sustainable constructions, composite structures become more important and lead to slim and economic solutions. The determination of moment resistance for composite beams follows the rules for composite structures according to EN 1994-1-1. For the Plastic design it is still assumed, that each cross-sectional fibre can plastify without any limitation of strains. For normal composite beams in case of sagging moments and a high-lying Plastic Neutral Axis, the real moment resistance is slightly higher than the Plastic resistance. This is based on the large strains at the bottom side of the section, so that the lower steel flange reaches the solidification range. In case of sections with a large compression zone height xpl, a concrete failure in the compression zone can happen before reaching the Plastic moment resistance. In these cases a strain limit design, based on the strain-stress relationships of concrete and steel, becomes decisive. EN 1994-1-1 provides only for cross-sections of classes 1 and 2 in steel grades S420 and S460 a limitation of Plastic design. It is to point out, that the rotation capacity of a composite section is not only conditioned by the b/t ratio of the steel section, but also the concrete part has a significant impact. This applies not only for high steel grades. Though, in Eurocode 4 there are no further regulations given for sections with lower steel grades. Especially, the more and more upcoming integrated and compact composite sections underline the importance of such requirements. Therefore, the objective of the recent research is concentrated on the development of additional regulations, to consider the influence of concrete compression zone height onto the moment resistance of composite beams

Zhang Qingjie - One of the best experts on this subject based on the ideXlab platform.

  • Limitations of Plastic bending resistance for composite beams deviated from strain-limitation
    'Elsevier BV', 2021
    Co-Authors: Schäfer Markus, Zhang Qingjie, Braun Matthias, Banfi Mike
    Abstract:

    Due to the demand for sustainable constructions, composite structures have become more important and lead to slim and economic solutions with a low structural self-weight. EN 1994-1-1 distinguishes between four different cross-section classes for the determination of moment resistance. For the Plastic moment resistance, it is assumed, that each cross-sectional fibre can plastify without any limit on the strain. For standard composite beams with sagging moments and a high Plastic Neutral Axis, Plastic resistance and strain-limited resistance give similar results. For sections with a large compression zone height xpl and limited rotation capacity, concrete failure in the compression zone can occur before the Plastic moment resistance Mpl,Rd, is reached. The strain limit design becomes critical. This paper points out the impact of the concrete part on the design of composite beams. A parametric study comparing Plastic and strain limited moment resistance of a considerable variety of cross-sections has been carried out to develop the beam design methods considering compression zone height for the next generation of Eurocodes

  • Impact of reinforcement to moment resistance of composite slabs
    2019
    Co-Authors: Zhang Qingjie, Schäfer Markus, Kurz Wolfgang
    Abstract:

    Composite slabs lead to slim and economic structural solutions with a low selfweight. The determination of their moment resistance follows the regulations presented in EN 1994-1-1 (2004) which are based on Plastic design methods. The current version of Eurocode 4 does not consider explicitly additional reinforcement in the ribs for sagging moment resistance. However, the construction industry requires this possibility in order to provide economical and flexible design. Regarding this situation, further investigations are necessary to prove the applicability of Plastic design methods. In the case of high bottom reinforcement ratio, a deep position of the Plastic Neutral Axis occurs, and concrete compression failure may happen before most parts of the profiled steel sheeting and reinforcement yield. This leads to an overestimation of the bending resistance according to the Plastic design method. A parametric study, based on approximately 290.000 different combinations of various cross-section geometries and materials, is provided to compare the Plastic moment resistance with the resistance determined by strain-limited design. The results show that limitations are necessary to be enabled for the general application of Plastic design methods

  • Plastic DESIGN FOR COMPOSITE BEAMS - ARE THERE ANY LIMITS?
    2019
    Co-Authors: Schäfer Markus, Zhang Qingjie, Banfi Mike
    Abstract:

    Due to the demand for sustainable constructions, composite structures have become more important and lead to slim and economic solutions with a low structural self-weight. EN 1994-1-1 differentiate four different cross-section classes for the determination of moment resistance. For the Plastic design of the moment resistance it is assumed, that each cross-sectional fibre can plastify without any limitation of the strains. For standard composite beams in case of sagging moments and a high-lying Plastic Neutral Axis, Plastic design and strain-limited design give similar results. In the case of sections with a large compression zone height xpl and limited rotation capacity, a concrete failure in the compression zone can occur before the Plastic moment resistance Mpl,Rd, is reached. The strain limit design becomes decisive. This paper points out the impact of the concrete part on the design of composite beams. A parametric study comparing Plastic and strain limited moment resistance of a considerable variety of cross-sections has been carried out to develop the beam design methods considering high compression zone height of next generation of Eurocodes

  • Particularities for Plastic design of composite beams with deep Plastic Neutral Axis
    2018
    Co-Authors: Schäfer Markus, Zhang Qingjie
    Abstract:

    The demand for sustainable constructions increases the importance of composite structures as they lead to slim and economical solutions with a low self-weight of the structure. The determination of the moment resistance for composite beams follows the rules stated in EN 1994-1-1. Based on the slenderness c/t of the compressed parts of the steel-section, composite cross-sections are classified into four cross-section classes. This classification indirectly reflects the rotation capacity and susceptibility to local buckling. For class 1 and 2 cross-sections, the Plastic moment resistance of the crosssection may be considered. Otherwise, an elastic design (for class 3) or an elastic design considering local buckling effects (for class 4) is necessary. If the Plastic resistance of the cross-section is assumed, it is considered that each cross-section fibre may plastify without limitation of the strain values. For normal composite beams subjected to the sagging moments and with a high Plastic Neutral Axis, the real moment resistance is quite greater than one obtained by the method of the Plastic design. For sections with a large compression zone, xpl, a concrete failure in the compression zone can happen before the Plastic moment resistance of the composite cross-section, Mpl,Rd, is reached. Strain limit design, therefore, becomes critical. EN 1994-1-1 provides a limitation of the Plastic design resistance only for sections with steel grades S420 and S460. However, there is no guidance given for lower steel grades or the determination of the corresponding concrete compression force. This paper points out, that the rotation capacity of a composite section is dependent on the slenderness of steel crosssection parts and on the behaviour of the concrete part. A comparison of Plastic and strain limited moment resistances as well as the analysis of partial shear diagram-based strain limited design results in new findings for the limits of Plastic design methods

Tsai-li Hsu - One of the best experts on this subject based on the ideXlab platform.

  • Investigation and Evaluation of Composite Girders based on 2005 AISC
    土木工程學系所, 2014
    Co-Authors: Tsai-li Hsu
    Abstract:

    早期建築物及公路橋樑均需採用大量鋼筋混凝土，結構本身靜載重大使得建築物高度、橋樑跨度因此受到限制。鋼結構設計因材料、理論與實務設計漸趨成熟及詳細，加上材料本身具有靜載重較輕、良好的韌性、耐震性佳、施工快速等優點使得建築物高度、橋樑跨度均可加大。 目前環保意識高漲注重材料回收再利用精神，將來結構物老舊時拆除較容易，且現場施工期程更能大幅縮短情況下，故合成梁設計方式普遍使用建築物樓板及長跨度橋樑結構設計中。美國鋼構造協會(AISC) 對於合成梁之設計有兩種方法包括ASD與LRFD，目前最新2005版AISC將ASD一齊併入同一章節說明，2005 版AISC合成梁之設計折減係數由0.85改為0.9，唯其設計基本理論、精神相同。 本研究針對LRFD之合成梁基本理論根據與新規範設計公式(2005)進行有系統推導、整理比較，將計算相關過程寫成電腦程式快速分析符合資訊時代。The existing buildings and highway bridges are generally to adopt a large amount of concrete, and this makes the limit on height of buildings and the limit on length of bridge spans. The steel construction due to its theory and practice design is getting mature. The new steel material has the nature of light weight, good toughness, bearing the shaking and fast in construction. All of these make the use of steel structures to be more acceptable to the design professions. This also puts the structures including the buildings and bridges are widely used as compared with the concrete structures. It is the main concern in design profession that the green material should be used in future design cases. Therefore, the use of composite structures including the floor system in building and the composite girders in bridges is the required applications in future. According to the American Institute Steel Construction (AISC), there are two methods including ASD and LRFD to design composite girders, the latest edition, which is the 2005 AISC Specifications, combines the ASD into the LRFD. The composite girder designs in the 2005 AISC Specifications, the composite girder design have reduced the moment reduction coefficient from 0.85 to 0.9. However, the design basic theory and spirit are basically the same; this study intends to summarize the AISC (2005) composite girders according to basic theory and new design formulas. Derivations for some formulas, standard procedure for calculation, and computerized evaluation are also presented for the use of practicing engineers. The goal for a quick and exact solution for the evaluation of composite girders is therefore achieved.Abstract i Table of contents ii Chapter 1 Introduction 1 1.1 Background 1 1.2 Advantage and disadvantages 2 1.3 Objectives 3 Chapter 2 AISC formulas for composite girders 6 2-1 Plastic Neutral Axis (PNA) is located inside the concrete slab without formed deck 6 2-2 Plastic Neutral Axis (PNA) is located inside the top flange of steel without formed deck 7 2-3 Plastic Neutral Axis (PNA) is located inside the web of steel without formed deck 8 2-4 Plastic Neutral Axis (PNA) is located inside the concrete slab with formed deck 9 2-5 Plastic Neutral Axis (PNA) is located inside the steel flange with formed deck 10 2-6 Plastic Neutral Axis (PNA) is located inside the steel web with formed deck 11 Chapter 3 Computerized Evaluation on Composite Girders 12 3-1 Input file format 12 3-2 Schematic notations used in computer program 12 3-3 Flow chart 16 3-4 The source code of the program 19 Chapter 4 Illustrated Examples 24 4-1 PNA is located inside the concrete slab 24 4-2 PNA is located inside the top flange of steel 36 4-3 PNA is located inside the web of steel 50 4-4 Partially composite girders 64 Chapter 5 Conclusions 84 References 85 Appendix A A-1 Appendix B B-1 Appendix C C-1 Appendix D D-

Banfi Mike - One of the best experts on this subject based on the ideXlab platform.

  • Limitations of Plastic bending resistance for composite beams deviated from strain-limitation
    'Elsevier BV', 2021
    Co-Authors: Schäfer Markus, Zhang Qingjie, Braun Matthias, Banfi Mike
    Abstract:

    Due to the demand for sustainable constructions, composite structures have become more important and lead to slim and economic solutions with a low structural self-weight. EN 1994-1-1 distinguishes between four different cross-section classes for the determination of moment resistance. For the Plastic moment resistance, it is assumed, that each cross-sectional fibre can plastify without any limit on the strain. For standard composite beams with sagging moments and a high Plastic Neutral Axis, Plastic resistance and strain-limited resistance give similar results. For sections with a large compression zone height xpl and limited rotation capacity, concrete failure in the compression zone can occur before the Plastic moment resistance Mpl,Rd, is reached. The strain limit design becomes critical. This paper points out the impact of the concrete part on the design of composite beams. A parametric study comparing Plastic and strain limited moment resistance of a considerable variety of cross-sections has been carried out to develop the beam design methods considering compression zone height for the next generation of Eurocodes

  • Plastic DESIGN FOR COMPOSITE BEAMS - ARE THERE ANY LIMITS?
    2019
    Co-Authors: Schäfer Markus, Zhang Qingjie, Banfi Mike
    Abstract:

    Due to the demand for sustainable constructions, composite structures have become more important and lead to slim and economic solutions with a low structural self-weight. EN 1994-1-1 differentiate four different cross-section classes for the determination of moment resistance. For the Plastic design of the moment resistance it is assumed, that each cross-sectional fibre can plastify without any limitation of the strains. For standard composite beams in case of sagging moments and a high-lying Plastic Neutral Axis, Plastic design and strain-limited design give similar results. In the case of sections with a large compression zone height xpl and limited rotation capacity, a concrete failure in the compression zone can occur before the Plastic moment resistance Mpl,Rd, is reached. The strain limit design becomes decisive. This paper points out the impact of the concrete part on the design of composite beams. A parametric study comparing Plastic and strain limited moment resistance of a considerable variety of cross-sections has been carried out to develop the beam design methods considering high compression zone height of next generation of Eurocodes

Chang Yen-hung - One of the best experts on this subject based on the ideXlab platform.

  • Analysis and Investigation of Composite Girders based on AISC Specifications-ASD
    土木工程學系所, 2014
    Co-Authors: Chang Yen-hung
    Abstract:

    複合梁(composite girders)係由W型鋼、I型鈑梁、混凝土、鋼製浪形鈑及剪力釘等所組成，現今之鋼結構建築與橋梁工程均已大量使用複合梁，早期AISC規範分別提供工程界兩種複合梁的設計方法，即ASD (Allowable Stress Design)設計及LRFD (Load and Resistance Factor Design)設計，目前最新2005版AISC規範已將ASD設計與LRFD設計合併為同一版本，即2005 AISC Manual of Steel Construction / 13th edition。 本研究分別就1989 AISC ASD與2005 AISC規範以理論方法及ASD設計手冊之查表方法，探討分析複合梁之斷面容許彎矩，經由理論推導說明規範公式之基本精神，進而提昇設計之品質。 ASD設計手冊之表格提供使用者分析所需之斷面性質，但僅限於一些常用斷面，同時也牽涉到內插等相關問題，對於工程師而言有使用上之限制。本研究提供一個較無限制的理論分析，基本上可適用於任何W型或I型梁之複合梁斷面，讓工程師有更多的斷面選擇，本研究也將理論方法撰寫成電腦程式，以提供使用者一個正確且快速的分析與設計工具。Composite beams have been widely used in both building and bridge structures. The specified composite beams in this research consist of W-shaped rolled/welded sections, concrete, formed steel decks, and shear connectors. The AISC specifications provide two methods for analysis and design, which include the ASD (Allowable Stress Design) and the LRFD (Load and Resistance Factor Design). A new version of AISC specifications published in 2005 (13th edition) combined the ASD and LRFD methods into one design specification. In this study, the flexural strength of composite beams for flexural was analyzed and compared among the 1989 AISC ASD specification and the 2005 AISC specification for their basic theories and design principles. It was found that the design values from the tables of the AISC design manuals are basically the same as the ones obtained from theory. The design using the tables of design manuals is limited by its available sections being listed in the design manuals. Illustrated examples to evaluate the flexural strength of the composite girders were presented. This intends to show the ways to obtain the design strength for various composite girders according the previous and current ASD methods. The comparison was given to see the differences among these old and new specifications. A more generalized method proposed to calculate any sizes of rolled W-type or built-up I-type composite girders was presented in this study. A computer program has been developed to furnish a faster yet reasonable design solution for practicing engineers.Table of Contents Abstract................................................i Table of contents..................................... ii Chapter 1 Introduction..................................1 1.1 Composite construction..............................1 1.2 Historical background...............................1 1.3 Advantages and disadvantages........................2 1.4 Objectives..........................................2 Chapter 2 AISC formulas of composite girders............5 2.1 Plastic Neutral Axis (PNA) is inside the concrete slab....................................................5 2.1.1 PNA is inside the concrete slab without formed deck (ASD-2005).............................................5 2.1.2 PNA is inside the concrete slab with formed deck (ASD-2005).............................................6 2.2 Plastic Neutral Axis (PNA) is located inside the top flange of steel.........................................7 2.2.1 PNA is located inside the top flange of steel without formed deck (ASD-2005).........................7 2.2.2 PNA is located inside the top flange of steel with formed deck (ASD-2005).................................8 2.3 Plastic Neutral Axis (PNA) is located inside the web of steel................................................9 2.3.1 PNA is located inside the web of steel without formed deck (ASD-2005).................................9 2.3.2 PNA is located inside the web of steel with formed deck (ASD-2005).......................................10 2.4 Elastic Neutral Axis (ENA) is inside the concrete slab ..............................................11 2.4.1 ENA is inside the concrete slab without formed deck (ASD-1989)............................................11 2.4.2 ENA is inside the concrete slab with formed deck (ASD-1989)............................................12 2.5 Elastic Neutral Axis (ENA) is located inside the top flange of steel........................................13 2.5.1 ENA is located inside the top flange of steel without formed deck (ASD-1989)........................13 2.5.2 ENA is located inside the top flange of steel with formed deck (ASD-1989)................................14 2.6 Elastic Neutral Axis (ENA) is located inside the web of steel...............................................15 2.6.1 ENA is located inside the web of steel without formed deck (ASD-1989)................................15 2.6.2 ENA is located inside the web of steel with formed deck (ASD-1989).......................................16 Chapter 3 Computerized evaluation of composite girders 17 3.1 Input file format..................................17 3.2 Schematic notations used in computer program.......17 3.3 Flow chart.........................................21 3.4 The source code of the program.....................24 Chapter 4 Illustrated examples.........................29 4.1 PNA/ENA is located inside the concrete slab........29 4.2 PNA/ENA is located inside the top flange of steel..39 4.3 PNA/ENA is located inside the web of steel.........49 4.4 Partially composite girder.........................59 Chapter 5 Conclusions...................................71 References.............................................73 Appendix A............................................A-1 Appendix B............................................B-1 Appendix C............................................C-1 Appendix D............................................D-1 Appendix E............................................E-1 Appendix F............................................F-