Yuhshi Fukumoto

Behaviour of steel-to-concrete connections under combined axial force and cyclic bending

Abstract Experimental study is completed on the behaviour of end-plate-type steel-to-concrete mixed connections under combined compressive normal force and cyclic bending. The main focus of the research in on the rotational stiffness of the mixed connection and its cyclic deterioration. The initial elastic stiffness is analyzed under different values of constant compressive axial forces. Interpretation and definition of rotational stiffness are introduced. The compressive axial force significantly increases the rotational stiffness, depending on the structural solution. Characteristics of the ultimate behaviour are determined under increasing cyclic bending moment and constant axial force. The tested mixed connections are classified according to strength and rigidity using the moment-rotation envelope curves. The cyclic characteristics of the moment-rotation response of the joints are analyzed. Early deterioration of the rotational stiffness is observed.

Local buckling strength of closed polygon folded section columns

Abstract The local buckling behavior of regular polygonal, short length steel columns, fabricated by welding two half sections made of folded steel plates, is described. The polygonal sections are composed of five different section profiles with four to eight sides and each profile having component plates with one to four varied width-to-thickness ratios. A total of 15 specimens are used in the compression test, sustaining uniform compression stress in the fixed end condition. Accurate measurements of welding and cold-forming residual stresses and geometric imperfections were taken prior to testing and are presented in this paper. The test strengths are compared with the current plate buckling code in Japan and with the ECCS recommendations for unstiffened circular cylinders. The empirical design formula based on the test data is also presented to predict the local buckling strength of the polygonal section columns.

Deformation analysis of locally buckled steel compression members

Abstract A numerical study is presented on the local and overall interaction buckling behavior of steel compression members of welded box sections. Accurate moment-thrust-curvature curves ( M-P-Φ curves) of locally buckled stub-columns are first computed with residual stresses and initial out-of-flatness of component plates being taken into consideration. The computed M-P-Φ curves are then integrated along the member axis to obtain the overall load-deformation characteristics of compression members. The effect of initial out-of-straightness of the member is included in the procedures. The numerical results are compared well with available test results of eccentrically loaded box columns. The numerical results are further utilized to check the adequacy of design formulae proposed previously by the authors. It has been found that a slight modification to the original formulae leads to better design formulae.

Theoretical study of ultimate load of locally buckled stub columns loaded eccentrically

Abstract This paper is concerned with the post buckling behavior and ultimate load-carrying capacity of thin-walled cold formed and welded stub columns subjected to a constant load eccentricity or a constant compression eccentricity. The analysis is based on the combined geometric and material nonlinear finite strip method in association with modified Ilushin yielding function. The emphasis is placed on the numerical studies on the effects of the loading types, load eccentricities and initial plate imperfections as well as the width-thickness ratios of the plates and the aspect ratios of the sections on the post buckling behavior and ultimate load-carrying capacity of thin-walled stub columns. The comparison of the theoretical results of this study with the experimental results conducted by X. Zhang (Ph.D. Thesis, Technical University, Darmstadt, 1989) is made and an agreement between both is very satisfactory.

Multi-surface model application to beam-columns subjected to cyclic loads

Abstract This paper deals with an analytical study of the cyclic behaviour of structural members by employing a multi-surface model for material nonlinearity. Extensive numerical studies of tubular beam-columns have been performed with the special stress-strain relationship of cold-formed material. These numerical results are compared with test results by Sherman. It can be concluded from the present study that (i) the multi-surface model based on a special stress-strain relation for the cold-formed material gives excellent agreement with the experimental results by Sherman, for investigation of the cyclic behaviour of tubular beam-columns and (ii) the multi-surface model is suitable for analyses of structural members in general and cold-formed tubular beam-columns in particular, under cyclic loading conditions.

Experimental and numerical analysis database on structural stability

Test data are an invaluable resource for structural engineering research. In this paper, a numerical database system is built for material properties of steels, steel columns, steel beams and unstiffened steel plates, etc. The database is used to clarify the strength variations of material properties and to obtain the mean value and the coefficient of variation of each member strength. In addition, these values are compared with existing design formulas. The database is further developed in the shape of a structural test information-based system. This system includes database functions, test data evaluation functions, reference retrieval functions and technical terms explanation functions. The usefulness of the knowledge base approach for representing the test data is proved and the potential and problems of the system are clarified.

Steel bridge construction in Japan

Abstract This paper briefly introduces the recent steel cable-stayed and suspension bridge construction in Japan. The big bridge projects in the highway network construction of the bay-shore routes in the Tokyo Bay, the Osaka Bay and the Ise Bay along the Pacific Ocean side are described. The Seto-Ohashi Bridge Route of 13·1 km, which skips five islands of the Inland Sea between Honshu and Shikoku, was opened in April, 1988. The Akashi-Kaikyo suspension bridge (960 + 1990 + 960 m) is now under construction and will be completed in 1998. The Trans-Tokyo Bay high-way project, which includes a total length of 5-km steel box girder bridges, is under construction, and the Kansai International Airport project is under progress in the Osaka Bay with 5-km truss-type access bridges for highways and railways. Steel consumption in bridge construction and steel bridge stock is also mentioned.

Local stresses at the intersection of cross-beam flange with box-girder web

Abstract Local stresses at the intersection of a top flange of a cross beam with a box-girder web are investigated analytically and experimentally. Finite element analyses of a T-shaped welded joint and a loading test of a cantilever beam of acrylic material reveal that a local stress which is different from the one caused by the stress concentrations at a weld toe is developed at the intersection. Finite element analyses of an I-section beam show that the restraint of the vertical deformation of the cross beam at the box-girder web induces the local stress. It is pointed out that the local stress must be considered in fatigue design. A method of determining the local stress is proposed.

Moment-rotation model of steel-to-concrete end-plate connections

Publisher Summary This chapter introduces a prediction model for the moment-rotation behavior of endplate type steel-to-concrete connections under combined axial force and bending moment. The developed model predicts the global response of the connection from the local behavior of the “tension” and “compression” zones. Steel-to-concrete mixed connections are connecting steel, concrete, reinforced concrete and composite structural elements. End-plate type mixed connections are applied in steel beam-to-reinforced concrete or composite column joints and steel or composite column bases. The load-deformation relationships of the zones are analyzed by two nonlinear 2D FEM models. The calculated moment-rotation curves are presented and compared to the experimental results and to a simplified analytical method. It is concluded that the proposed method provides good prediction for the initial range of the moment-rotation relationship but underestimates the ultimate moment capacity.

Performance of mixed connections under combined loads

Publisher Summary This chapter discusses the performance of steel-concrete mixed connections under combined loads and also provides some results and findings through a series of experiments. . The type of connection is endplate type. The connection is proposed for jointing steel members. Through the experimental observation, capabilities are examined. The basic concept of the joint is a usage of reinforced concrete instead of bolts for the connection. Since concrete can take any shape by nature, fairly larger tolerance allowed on site work is possible. The connection can be designed so as to have smooth transmission of forces from one member to the other, and to have certain capacity required. In addition, sufficient ductility may also be expected if the mutual restraint due to the interaction of steel and concrete materials is effectively used. In this chapter, the mixed connection, which consists of steel endplates and a reinforced concrete segment is proposed for the joint of steel members. Since the performance of the connection affects both the behavior and the strength of the whole structure, the chapter is dedicated to clarify the performance of the connection.