Numerical studies of steel-concrete-steel sandwich walls with J-hook connectors subjected to axial loads

Zhenyu Huang,J.Y. Richard Liew 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.3

Steel-concrete-steel (SCS) sandwich composite wall has been proposed for building and offshore constructions. An ultra-lightweight cement composite with density1380 kg/m³ and compressive strength up to 60 MPa is used as core material and inter-locking J-hook connectors are welded on the steel face plates to achieve the composite action. This paper presents the numerical models using nonlinear finite element analysis to investigate the load displacement behavior of SCS sandwich walls subjected to axial compression. The results obtained from finite element analysis are verified against the test results to establish its accuracy in predicting load-displacement curves, maximum resistance and failure modes of the sandwich walls. The studies show that the inter-locking J-hook connectors are subjected to tension force due to the lateral expansion of cement composite core under compression. This signifies the important role of the interlocking effect of J-hook connectors in preventing tensile separation of the steel face plates so that the local buckling of steel face plates is prevented.

Ultimate strength behavior of steel-concrete-steel sandwich beams with ultra-lightweight cement composite, Part 2: Finite element analysis

Jia-Bao Yan,J.Y. Richard Liew,Min-Hong Zhang 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.4

Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of 1,450 kg/㎥ has been developed and used in the steel-concrete-steel (SCS) sandwich structures. This paper investigates the structural performances of SCS sandwich composite beams with ULCC as filled material. Overlapped headed shear studs were used to provide shear and tensile bond between the face plate and the lightweight core. Three-dimensional nonlinear finite element (FE) model was developed for the ultimate strength analysis of such SCS sandwich composite beams. The accuracy of the FE analysis was established by comparing the predicted results with the quasi-static tests on the SCS sandwich beams. The FE model was also applied to the nonlinear analysis on curved SCS sandwich beam and shells and the SCS sandwich beams with J-hook connectors and different concrete core including ULCC, lightweight concrete (LWC) and normal weight concrete (NWC). Validations were also carried out to check the accuracy of the FE analysis on the SCS sandwich beams with J-hook connectors and curved SCS sandwich structure. Finally, recommended FE analysis procedures were given.

Steel-Concrete-Steel Sandwich Composite Structures Subjected to Extreme Loads

Zhenyu Huang,J Y Richard Liew 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4

This paper summarizes the latest research and development work on steel-concrete-steel (SCS) sandwich composite structures for the use as Arctic offshore platform, and to resist impact and blast loads. Current development of ultra-lightweight cement composite (ULCC) and a floatable structural cement composite (FSCC) to be used as infilled materials for SCS sandwich structure are presented. This paper aims to advance the application of SCS sandwich composite with the use of steel plate and lightweight concrete materials. A series of tests on lightweight SCS sandwich panels with shear connectors has been carried out. The superior performance of SCS sandwich panel is demonstrated. The results show that SCS sandwich with novel J-hook connectors is effective in preventing plate separation from concrete core, maintaining the structural integrity.

Design of High Strength Concrete Filled Tubular Columns For Tall Buildings

Liew, J.Y. Richard,Xiong, M.X.,Xiong, D.X. Council on Tall Building and Urban Habitat Korea 2014 International journal of high-rise buildings Vol.3 No.3

Ultra-high strength concrete and high tensile steel are becoming very attractive materials for high-rise buildings because of the need to reduce member size and structural self-weight. However, limited test data and design guidelines are available to support the applications of high strength materials for building constructions. This paper presents significant findings from comprehensive experimental investigations on the behaviour of tubular columns in-filled with ultra-high strength concrete at ambient and elevated temperatures. A series of tests was conducted to investigate the basic mechanical properties of the high strength materials, and structural behaviour of stub columns under concentric compression, beams under moment and slender beam-columns under concentric and eccentric compression. High tensile steel with yield strength up to 780 MPa and ultra-high strength concrete with compressive cylinder strength up to 180 MPa were used to construct the test specimens. The test results were compared with the predictions using a modified Eurocode 4 approach. In addition, more than 2000 test data samples collected from literature on concrete filled steel tubes with normal and high strength materials were also analysed to formulate the design guide for implementation in practice.

Advanced Analysis of Pre-tensioned Bowstring Structures

J Y Richard Liew,JIn-Jun Li 한국강구조학회 2006 International Journal of Steel Structures Vol.6 No.3

Bowstring stel structure is a novel cable-tensioned space structure in which out-of-plane stability is ensured by pre-tensionedbeen developed to predict the collapse behavior of pre-tensioned steel structures. Special emphasis is placed on the modelingof pre-tensioned cable and the nonlinear beam-column conections. Novel connectors conecting rectangular hollow sectionbeam and column have ben proposed and tested to obtain their moment-rotation relationship. Numerical work on three-dimensional bowstring structures shows that their load-displacement behavior is dependent not only on structural

Moment curvature method for fire safety design of steel beams

J.Y. Richard Liew,H.X. Yu 국제구조공학회 2004 Steel and Composite Structures, An International J Vol.4 No.3

This paper presents a moment-curvature method that accounts for the strength deterioration of steel at elevated temperature in estimating the response of steel beams exposed to fire. A modification to the EC4 method is proposed for a better estimation of the temperature distribution in the steel beam supporting a concrete slab. The accuracy of the proposed method is verified by comparing the results with established test results and the nonlinear finite element analysis results. The beam failure criterion based on a maximum strain of 0.02 is proposed to assess the limiting temperature as compared to the traditional criteria that rely on deflection limit or deflection rate. Extensive studies carried out on steel beams with various span lengths, load ratios, beam sizes and loading types show that the proposed failure criterion gives consistent results when compared to nonlinear finite element results.

State-of-the-art of advanced inelastic analysis of steel and composite structures

J.Y. Richard Liew 국제구조공학회 2001 Steel and Composite Structures, An International J Vol.1 No.3

This paper provides a state-of-the-art review on advanced analysis models for investigating the load-displacement and ultimate load behaviour of steel and composite frames subjected to static gravity and lateral loads. Various inelastic analysis models for steel and composite members are reviewed. Composite beams under positive and negative moments are analysed using a moment-curvature relationship which captures the effects of concrete cracking and steel yielding along the members length. Beam-to-column connections are modeled using rotational spring. Building core walls are modeled using thin-walled element. Finally, the nonlinear behaviour of a complete multi-storey building frame consisting of a centre core-wall and the perimeter frames for lateral-load resistance is investigated. The performance of the total building system is evaluated in term of its serviceability and ultimate limit states.

Practical design guidlines for semi-continuous composite braced frames

J.Y. Richard Liew,K.L. Looi,Brian Uy 국제구조공학회 2001 Steel and Composite Structures, An International J Vol.1 No.2

This paper presents a simplified approach for the design of semi-continuous composite beams in braced frames, where specific attention is given to the effect of joint rotational stiffness. A simple composite beam model is proposed incorporating the effects of semi-rigid end connections and the nonprismatic properties of a ‘cracked’ steel-concrete beam. This beam model is extended to a sub-frame in which the restraining effects from the adjoining members are considered. Parametric studies are performed on several sub-frame models and the results are used to show that it is possible to correlate the amount of moment redistribution of semi-continuous beam within the sub-frame using an equivalent stiffness of the connection. Deflection equations are derived for semi-continuous composite beams subjected to various loading and parametric studies on beam vibrations are conducted. The proposed method may be applied using a simple computer or spreadsheet program.

Experimental and analytical investigation of composite columns made of high strength steel and high strength concrete

Binglin Lai,J.Y. Richard Liew,Mingxiang Xiong 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.1

Composite columns made of high strength materials have been used in high-rise construction owing to its excellent structural performance resulting in smaller cross-sectional sizes. However, due to the limited understanding of its structural response, current design codes do not allow the use of high strength materials beyond a certain strength limit. This paper reports additional test data, analytical and numerical studies leading to a new design method to predict the ultimate resistance of composite columns made of high strength steel and high strength concrete. Based on previous study on high strength concrete filled steel tubular members and ongoing work on high strength concrete encased steel columns, this paper provides new findings and presents the feasibility of using high strength steel and high strength concrete for general double symmetric composite columns. A nonlinear finite element model has been developed to capture the composite beam-column behavior. The Eurocode 4 approach of designing composite columns is examined by comparing the test data with results obtained from code's predictions and finite element analysis, from which the validities of the concrete confinement effect and plastic design method are discussed. Eurocode 4 method is found to overestimate the resistance of concrete encased composite columns when ultra-high strength steel is used. Finally, a strain compatibility method is proposed as a modification of existing Eurocode 4 method to give reasonable prediction of the ultimate strength of concrete encased beam-columns with steel strength up to 900 MPa and concrete strength up to 100 MPa.

Plastic Hinge Analysis of Composite Frames under Column Loss Scenario

S. Jeyarajan,J.Y. Richard Liew,C. G. Koh 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.3

This paper presents a plastic hinge analysis approach for static and dynamic assessment of composite frames under column loss scenarios. The proposed plastic hinge analysis method can be implemented using spreadsheet programming and it is computational less expensive compared to numerical analysis. A step-by-step first-order elastic-plastic analysis by tracking the formation of plastic hinge in a composite floor is performed until a collapse mechanism is formed to establish the static loaddisplacement behaviour and collapse load of a composite floor subject to sudden column loss. Floor deflections corresponding to the formation of each plastic hinge are evaluated to predict the static load-deformation response of composite frame. The composite floor joint effects can be included in the plastic hinge analysis by calculating the joints’ axial resistance and moment resistance using the Eurocodes’ component method. A dynamic assessment approach is then used to predict the dynamic response of frame due to sudden column loss. The accuracy of the proposed method is verified by comparing the predicted results with those from the established test and numerical results available in the literature.