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Papers by Wibisono Hartono

Composite Behaviour of Half Castellated Beam with Concrete Top Slab

Elsevier eBooks, 1996

Publisher Summary This chapter presents both experimental and numerical studies of composite half... more Publisher Summary This chapter presents both experimental and numerical studies of composite half castellated beams. Six specimens of two different sizes with 1000 mm by 120 mm concrete top slab were fabricated. A different number of openings makes the length of specimens varies from 2.9 m to 5.7 m. They were tested to failure as simply supported beams under the application of two concentrated loads. The first observed failure pattern is the cracking of the concrete slab in the longitudinal axis of the beam. It was followed by a transverse cracking of the slab near the supports. Final failure occurred when the first web-post of the steel section buckled. The nonlinear behavior and corresponding failure load and mode were then compared with those obtained through numerical modeling. The chapter discusses that a finite element method (FEM) software was used to model the composite beam in which load imperfection was introduced to simulate the real behavior. Good agreement between the numerical and experimental results is observed. For comparison purpose, a half-castellated steel beam without concrete top slab was also tested. The beam failed in lateral torsional buckling, which shows that the addition of a concrete top slab greatly enhances the beam capacity.

Doboku Gakkai Ronbunshu, Apr 20, 1987

This paper presents a method to trace the bifurcation equilibrium paths utilizing the Newton-Raph... more This paper presents a method to trace the bifurcation equilibrium paths utilizing the Newton-Raphson method. The initial guess solutions on the bifurcation paths are obtained by considering the higher order terms of the Taylor series expansion of the incremental equations at the critical points.

Imperfection behavior of elastic nonlinear systems illustrated by a three-degree-of-freedom model

AIAA Journal, Sep 1, 1991

A simple three-degree-of-freedom spring model system is presented to study the instability behavi... more A simple three-degree-of-freedom spring model system is presented to study the instability behavior of perfect and imperfect systems. The model has all known types of critical points: the stationary point and symmetric and asymmetric bifurcation points. By changing three parameters of the model, the behavior of the system can be altered and investigated. Numerical results are presented to demonstrate instability behavior of perfect and imperfect elastic nonlinear systems. Major findings are 1) an equilibrium path may terminate at a point and jump to another point even when geometric change is continuous; 2) the optimum solutions for the mode of imperfection that gives the lowest carrying capacity may also terminate at a point and jump to another point even when norms of imperfections are changed continuously; 3) an iterative process most likely diverges when the aforementioned two conditions take place unless an initial guess solution closer to the jumped position is used; 4) even for the same mode of imperfection, the load carrying capacities are not necessarily the same when norms of initial imperfections approach zero, depending on the signs of the mode; and 5) when hidden critical points are present, the structure is extremely sensitive to imperfection.

Compression Tests of Stainless Steel Tubular Members

Journal of Structural Engineering-asce, Jun 1, 2002

A series of tests consisting of three cross-section geometries was performed on cold-formed stain... more A series of tests consisting of three cross-section geometries was performed on cold-formed stainless steel circular hollow section (CHS) columns compressed between fixed ends. The specimens were cold rolled from stainless steel sheets. The tests were performed over a range of column lengths, which involved local buckling and overall flexural buckling. Measurements of overall geometric imperfections and material properties were conducted. The test strengths are compared with the design strengths predicted using the American, Australian/New Zealand and European specifications for cold-formed stainless steel structures as well as the column strengths obtained from the design rules proposed by Rasmussen and Hancock in 1993 and Rasmussen and Rondal in 1997. Generally, the specifications unconservatively predict the strengths of the tested CHS columns, while Rasmussen and Hancock; and Rasmussen and Rondal conservatively predict the column strengths. The reliability of these design rules is evaluated using reli...

Experimental investigation of stainless steel circular hollow section columns

Elsevier eBooks, 2001

Doboku Gakkai Ronbunshu, Apr 20, 1988

Bifurcation behavioral characteristics of a cone-shaped axisymmetric elastic space truss made of ... more Bifurcation behavioral characteristics of a cone-shaped axisymmetric elastic space truss made of n elastic members with n-axes of symmetry are studied. Equilibrium equations of the truss are investigated using cylindrical coordinates to verify the existence of 2 n bifurcation paths. The number of paths increases proportionally to the member number n. The equilibrium equations show this increase of bifurcation paths by the vanishing of lower-order terms, resulting in non-vanishing terms with higher-order nonlinearity. The geometric symmetry of the truss results in rotational symmetry of the equilibrium equations and of the bifurcation paths.

Doboku Gakkai Ronbunshu, Apr 20, 1987

A Study on the stability and the behavior at the critical points of nonlinear discrete structural... more A Study on the stability and the behavior at the critical points of nonlinear discrete structural system is presented utilizing the Taylor expansion of the governing algebraic equations. The results are compared with the previous works on the same subject. This method is found to be much simpler to explain the subject than the perturbation method together with the energy function which is the technique mostly used in literature. Three examples on plane and space elastic truss structures are presented to illustrate the analytical results. Keywords: stability, bifurcation, nonlinear structural analysis 1. perturbation technique as Refs. 2 and 3. In his analysis the derivatives with respect to a loading parameter are present in addition to the derivatives with respect to the components of displacement vector as in Refs. 2 and 3. The same method of Taylor expansion is used to study the behavior at the critical points5). Recently, Nishino et al.6) studied the behavior at critical points by examining the solution of linear singular

Discussion: Elastica of Simple Variable-Arc-Length Beam Subjected to End Moment

Journal of Engineering Mechanics-asce, 1997

ZAMM, 2001

This paper investigates the large displacement post-buckling behavior of a column with central br... more This paper investigates the large displacement post-buckling behavior of a column with central brace using the elastica solution. The method is able in predicting the buckling load and in tracing the exact post-buckling paths, both primary and secondary paths. Depending on the brace stiffness, different shapes of symmetrical and anti-symmetrical post-buckling paths can be shown to exist. Whilst previous work reported only one threshold value of brace stiffness, the results also show the existence of infinite number of threshold values, each indicates a change in the post-buckling behavior.

Behavior of variable length elastica with frictional support under follower force

Mechanics Research Communications, 2000

A floating tied system for an offshore airport

Ocean Engineering, 1998

This paper presents a new system for a floating offshore airport. It consists of an assembly of p... more This paper presents a new system for a floating offshore airport. It consists of an assembly of precast boxes, each of them tied with a cable system. The (tension) cable system acts as a bracing against any lateral forces during airport operation. It also prevents the boxes from oscillating and moving during the airport construction and operation. The space inside each box can be utilized for other purposes. A top slab system consisting of precast and cast in situ concrete slabs will form the platfonn of the airport. Finally, a proposed method of construction is also presented. The new system offers an easier construction method and allows future airport extension and even relocation.

On improving the student learning interest of subject C302 : design of steel and concrete structures 1

On the influence of the imperfection on the carrying capacity of geometrically nonlinear structures

Influential Mode of Imperfection on Carrying Capacity of Structures

J Eng Mech Asce, 1989

Elastica of Cantilever Beam under Two Follower Forces

Advances in Structural Engineering

An alternative structural system for reclamation

This report presents a study of possible implementation of a new system of floating airport. Unli... more This report presents a study of possible implementation of a new system of floating airport. Unlike the existing other systems that are also under research, it does not move and oscillate under the action of waves and wind, however it still makes use of the buoyancy of sea water to resist the gravity forces. Study of structure behaviour under static load combinations and dynamic analysis under seismic excitation are included in this project. The static analysis is presented in this report. RG 18/94

Elastic nonlinear behavior of truss system under follower and non-follower forces

Computers & Structures, 1997

A floating tied platform for generating energy from ocean current

Renewable Energy, 2002

This paper presents a proposal for generating energy from the ocean current. A floating platform ... more This paper presents a proposal for generating energy from the ocean current. A floating platform tied with cable bracing system to concrete blocks anchored to seabed will house the generators and turbines. To show that the construction of the proposed floating structure is feasible, construction method is also proposed. Whilst more research and investigation are required, the proposed system might

A study of the stability and behavior at the critical point by the Taylor expansion

Doboku Gakkai Ronbunshu, 1987

Bifurcation behavior of an axisymmetric elastic space truss

Doboku Gakkai Ronbunshu, 1988

Composite Behaviour of Half Castellated Beam with Concrete Top Slab

Elsevier eBooks, 1996

Publisher Summary This chapter presents both experimental and numerical studies of composite half... more Publisher Summary This chapter presents both experimental and numerical studies of composite half castellated beams. Six specimens of two different sizes with 1000 mm by 120 mm concrete top slab were fabricated. A different number of openings makes the length of specimens varies from 2.9 m to 5.7 m. They were tested to failure as simply supported beams under the application of two concentrated loads. The first observed failure pattern is the cracking of the concrete slab in the longitudinal axis of the beam. It was followed by a transverse cracking of the slab near the supports. Final failure occurred when the first web-post of the steel section buckled. The nonlinear behavior and corresponding failure load and mode were then compared with those obtained through numerical modeling. The chapter discusses that a finite element method (FEM) software was used to model the composite beam in which load imperfection was introduced to simulate the real behavior. Good agreement between the numerical and experimental results is observed. For comparison purpose, a half-castellated steel beam without concrete top slab was also tested. The beam failed in lateral torsional buckling, which shows that the addition of a concrete top slab greatly enhances the beam capacity.

Doboku Gakkai Ronbunshu, Apr 20, 1987

This paper presents a method to trace the bifurcation equilibrium paths utilizing the Newton-Raph... more This paper presents a method to trace the bifurcation equilibrium paths utilizing the Newton-Raphson method. The initial guess solutions on the bifurcation paths are obtained by considering the higher order terms of the Taylor series expansion of the incremental equations at the critical points.

Imperfection behavior of elastic nonlinear systems illustrated by a three-degree-of-freedom model

AIAA Journal, Sep 1, 1991

A simple three-degree-of-freedom spring model system is presented to study the instability behavi... more A simple three-degree-of-freedom spring model system is presented to study the instability behavior of perfect and imperfect systems. The model has all known types of critical points: the stationary point and symmetric and asymmetric bifurcation points. By changing three parameters of the model, the behavior of the system can be altered and investigated. Numerical results are presented to demonstrate instability behavior of perfect and imperfect elastic nonlinear systems. Major findings are 1) an equilibrium path may terminate at a point and jump to another point even when geometric change is continuous; 2) the optimum solutions for the mode of imperfection that gives the lowest carrying capacity may also terminate at a point and jump to another point even when norms of imperfections are changed continuously; 3) an iterative process most likely diverges when the aforementioned two conditions take place unless an initial guess solution closer to the jumped position is used; 4) even for the same mode of imperfection, the load carrying capacities are not necessarily the same when norms of initial imperfections approach zero, depending on the signs of the mode; and 5) when hidden critical points are present, the structure is extremely sensitive to imperfection.

Compression Tests of Stainless Steel Tubular Members

Journal of Structural Engineering-asce, Jun 1, 2002

A series of tests consisting of three cross-section geometries was performed on cold-formed stain... more A series of tests consisting of three cross-section geometries was performed on cold-formed stainless steel circular hollow section (CHS) columns compressed between fixed ends. The specimens were cold rolled from stainless steel sheets. The tests were performed over a range of column lengths, which involved local buckling and overall flexural buckling. Measurements of overall geometric imperfections and material properties were conducted. The test strengths are compared with the design strengths predicted using the American, Australian/New Zealand and European specifications for cold-formed stainless steel structures as well as the column strengths obtained from the design rules proposed by Rasmussen and Hancock in 1993 and Rasmussen and Rondal in 1997. Generally, the specifications unconservatively predict the strengths of the tested CHS columns, while Rasmussen and Hancock; and Rasmussen and Rondal conservatively predict the column strengths. The reliability of these design rules is evaluated using reli...

Experimental investigation of stainless steel circular hollow section columns

Elsevier eBooks, 2001

Doboku Gakkai Ronbunshu, Apr 20, 1988

Bifurcation behavioral characteristics of a cone-shaped axisymmetric elastic space truss made of ... more Bifurcation behavioral characteristics of a cone-shaped axisymmetric elastic space truss made of n elastic members with n-axes of symmetry are studied. Equilibrium equations of the truss are investigated using cylindrical coordinates to verify the existence of 2 n bifurcation paths. The number of paths increases proportionally to the member number n. The equilibrium equations show this increase of bifurcation paths by the vanishing of lower-order terms, resulting in non-vanishing terms with higher-order nonlinearity. The geometric symmetry of the truss results in rotational symmetry of the equilibrium equations and of the bifurcation paths.

Doboku Gakkai Ronbunshu, Apr 20, 1987

A Study on the stability and the behavior at the critical points of nonlinear discrete structural... more A Study on the stability and the behavior at the critical points of nonlinear discrete structural system is presented utilizing the Taylor expansion of the governing algebraic equations. The results are compared with the previous works on the same subject. This method is found to be much simpler to explain the subject than the perturbation method together with the energy function which is the technique mostly used in literature. Three examples on plane and space elastic truss structures are presented to illustrate the analytical results. Keywords: stability, bifurcation, nonlinear structural analysis 1. perturbation technique as Refs. 2 and 3. In his analysis the derivatives with respect to a loading parameter are present in addition to the derivatives with respect to the components of displacement vector as in Refs. 2 and 3. The same method of Taylor expansion is used to study the behavior at the critical points5). Recently, Nishino et al.6) studied the behavior at critical points by examining the solution of linear singular

Discussion: Elastica of Simple Variable-Arc-Length Beam Subjected to End Moment

Journal of Engineering Mechanics-asce, 1997

ZAMM, 2001

This paper investigates the large displacement post-buckling behavior of a column with central br... more This paper investigates the large displacement post-buckling behavior of a column with central brace using the elastica solution. The method is able in predicting the buckling load and in tracing the exact post-buckling paths, both primary and secondary paths. Depending on the brace stiffness, different shapes of symmetrical and anti-symmetrical post-buckling paths can be shown to exist. Whilst previous work reported only one threshold value of brace stiffness, the results also show the existence of infinite number of threshold values, each indicates a change in the post-buckling behavior.

Behavior of variable length elastica with frictional support under follower force

Mechanics Research Communications, 2000

A floating tied system for an offshore airport

Ocean Engineering, 1998

This paper presents a new system for a floating offshore airport. It consists of an assembly of p... more This paper presents a new system for a floating offshore airport. It consists of an assembly of precast boxes, each of them tied with a cable system. The (tension) cable system acts as a bracing against any lateral forces during airport operation. It also prevents the boxes from oscillating and moving during the airport construction and operation. The space inside each box can be utilized for other purposes. A top slab system consisting of precast and cast in situ concrete slabs will form the platfonn of the airport. Finally, a proposed method of construction is also presented. The new system offers an easier construction method and allows future airport extension and even relocation.

On improving the student learning interest of subject C302 : design of steel and concrete structures 1

On the influence of the imperfection on the carrying capacity of geometrically nonlinear structures

Influential Mode of Imperfection on Carrying Capacity of Structures

J Eng Mech Asce, 1989

Elastica of Cantilever Beam under Two Follower Forces

Advances in Structural Engineering

An alternative structural system for reclamation

This report presents a study of possible implementation of a new system of floating airport. Unli... more This report presents a study of possible implementation of a new system of floating airport. Unlike the existing other systems that are also under research, it does not move and oscillate under the action of waves and wind, however it still makes use of the buoyancy of sea water to resist the gravity forces. Study of structure behaviour under static load combinations and dynamic analysis under seismic excitation are included in this project. The static analysis is presented in this report. RG 18/94

Elastic nonlinear behavior of truss system under follower and non-follower forces

Computers & Structures, 1997

A floating tied platform for generating energy from ocean current

Renewable Energy, 2002

This paper presents a proposal for generating energy from the ocean current. A floating platform ... more This paper presents a proposal for generating energy from the ocean current. A floating platform tied with cable bracing system to concrete blocks anchored to seabed will house the generators and turbines. To show that the construction of the proposed floating structure is feasible, construction method is also proposed. Whilst more research and investigation are required, the proposed system might

A study of the stability and behavior at the critical point by the Taylor expansion

Doboku Gakkai Ronbunshu, 1987

Bifurcation behavior of an axisymmetric elastic space truss

Doboku Gakkai Ronbunshu, 1988