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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Steel and Composite Structures
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Volume & Issues
Volume 19, Issue 6 - Dec 2015
Volume 19, Issue 5 - Nov 2015
Volume 19, Issue 4 - Oct 2015
Volume 19, Issue 3 - Sep 2015
Volume 19, Issue 2 - Aug 2015
Volume 19, Issue 1 - Jul 2015
Volume 18, Issue 6 - Jun 2015
Volume 18, Issue 5 - May 2015
Volume 18, Issue 4 - Apr 2015
Volume 18, Issue 3 - Mar 2015
Volume 18, Issue 2 - Feb 2015
Volume 18, Issue 1 - Jan 2015
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Shear strength analyses of internal diaphragm connections to CFT columns
Kang, Liping ; Leon, Roberto T. ; Lu, Xilin ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1083~1101
DOI : 10.12989/scs.2015.18.5.1083
Previous theoretical equations for the shear capacity of steel beam to concrete filled steel tube (CFT) column connections vary in the assumptions for the shear deformation mechanisms and adopt different equations for calculating shear strength of each component (steel tube webs, steel tube flanges, diaphragms, and concrete etc.); thus result in different equations for calculating shear strength of the joint. Besides, shear force-deformation relations of the joint, needed for estimating building drift, are not well developed at the present. This paper compares previously proposed equations for joint shear capacity, discusses the shear deformation mechanism of the joint, and suggests recommendations for obtaining more accurate predictions. Finite element analyses of internal diaphragm connections to CFT columns were carried out in ABAQUS. ABAQUS results and theoretical estimations of the shear capacities were then used to calibrate rotational springs in joint elements in OpenSEES simulating the shear deformation behavior of the joint. The ABAQUS and OpenSEES results were validated with experimental results available. Results show that: (1) shear deformation of the steel tube dominates the deformation of the joint; while the thickness of the diaphragms has a negligible effect; (2) in OpenSEES simulation, the joint behavior is highly dependent on the yielding strength given to the rotational spring; and (3) axial force ratio has a significant effect on the joint deformation of the specimen analyzed. Finally, modified joint shear force-deformation relations are proposed based on previous theory.
Determination of displacement distributions in welded steel tension elements using digital image techniques
Sozen, Sahin ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1103~1117
DOI : 10.12989/scs.2015.18.5.1103
It is known that material properties, connection quality and manufacturing methods are among the important factors directly affecting the behavior of steel connections and hence steel structures. The possible performance differences between a fabricated connection and its computer model may cause critical design problems for steel structures. Achieving a reliable design depends, however, on how accurately the material properties and relevant constitutive models are considered to characterize the behavior of structures. Conventionally, the stress and strain fields in structural steel connections are calculated using the finite elements method with assumed material properties and constitutive models. Because the conventional strain gages allow the measurement of deformation only at one point and direction for specific time duration, it is not possible to determine the general characteristics of stress-strain distributions in connections after the laboratory performance tests. In this study, a new method is introduced to measure displacement distribution of simple steel welded connections under tension tests. The method is based on analyzing digital images of connection specimens taken periodically during the laboratory tension test. By using this method, displacement distribution of steel connections can be calculated with an acceptable precision for the tested connections. Calculated displacements based on the digital image correlation method are compared with those calculated using the finite elements method.
Modeling and simulation of partially delaminated composite beams
Mahieddine, A. ; Ouali, M. ; Mazouz, A. ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1119~1127
DOI : 10.12989/scs.2015.18.5.1119
A finite-element model for beams with partially delaminated layers is used to investigate their behavior. In this formulation account is taken of lateral strains and the first-order shear deformation theory is used. Both displacement continuity and force equilibrium conditions are imposed between the regions with and without delamination. Numerical results of the present model are presented and its performance is evaluated for static and dynamic problems.
Experimental study on flexural behavior of splicing concrete-filled GFRP tubular composite members connected with steel bars
Chen, B.L. ; Wang, L.G. ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1129~1144
DOI : 10.12989/scs.2015.18.5.1129
Based on the experiment, this paper focuses on studying flexural behavior of splicing concrete-filled glass fiber reinforced polymer (GFRP) tubular composite members connected with steel bars. The test results indicated the confinement effects of GFRP tubes on the concrete core in compression zone began to produce, when the load reached about
-ultimate load), but the confinement effects in tensile zone was unobvious. In addition, the failure modes of composite members were influenced by the steel ratio of the joint. For splicing unreinforced composite members, the steel ratio more than 1.96% could satisfy the splicing requirements and the steel ratio 2.94% was ideal comparatively. For splicing reinforced specimen, the bearing capacity of specimen with 3.92% steel ratio was higher 21.4% than specimen with 2.94% steel ratio and the latter was higher 21.2% than the contrast non-splicing specimen, which indicated that the steel ratio more than 2.94% could satisfy the splicing requirements and both splicing ways used in the experiment were feasible. So, the optimal steel ratio 2.94% was suggested economically. The experimental results also indicated that the carrying capacity and ductility of splicing concrete-filled GFRP tubular composite members could be improved by setting internal longitudinal rebars.
Steel-CFRP composite and their shear response as vertical stirrup in beams
Uriayer, Faris A. ; Alam, Mehtab ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1145~1160
DOI : 10.12989/scs.2015.18.5.1145
An experimental study was conducted for the effectiveness of steel-CFRP composite (CFRP laminates sandwiched between two steel strips) as stirrups in concrete beam to carry shearing force and comparison was made with conventional steel bar stirrups. A total numbers of 8 concrete beams were tested under four point loads. Each beam measured 1,600 mm long, 160 mm width and 240 mm depth. The beams were composed of same grade of concrete, with same amount of flexural steel but different shear reinforcements. The main variables include, type of stirrups (shape of stirrups and number of CFRP layers used in each stirrup) and number of stirrups used in shear spans. After getting on an excellent closeness between the values of ultimate shear resistance and ultimate tensile load of steel-CFRP stirrups, it could be concluded that the steel-CFRP stirrups represent the effective solution of premature failure of FRP stirrups at the bends.
Energy dissipation of steel-polymer composite beam-column connector
Wang, Yun-Che ; Ko, Chih-Chin ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1161~1176
DOI : 10.12989/scs.2015.18.5.1161
The connection between a column and a beam is of particular importance to ensure the safety of civil engineering structures, such as high-rise buildings and bridges. While the connector must bear sufficient force for load transmission, increase of its ductility, toughness and damping may greatly enhance the overall safety of the structures. In this work, a composite beam-column connector is proposed and analyzed with the finite element method, including effects of elasticity, linear viscoelasticity, plasticity, as well as geometric nonlinearity. The composite connector consists of three parts: (1) soft steel; (2) polymer; and (3) conventional steel to be connected to beam and column. It is found that even in the linear range, the energy dissipation capacity of the composite connector is largely enhanced by the polymer material. Since the soft steel exhibits low yield stress and high ductility, hence under large deformation the soft steel has the plastic deformation to give rise to unique energy dissipation. With suitable geometric design, the connector may be tuned to exhibit different strengths and energy dissipation capabilities for real-world applications.
Cyclic test for beam-to-column abnormal joints in steel moment-resisting frames
Liu, Zu Q. ; Xue, Jian Y. ; Peng, Xiu N. ; Gao, Liang ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1177~1195
DOI : 10.12989/scs.2015.18.5.1177
Six specimens are tested to investigate the cyclic behavior of beam-to-column abnormal joints in steel moment-resisting frames, which are designed according to the principle of strong-member and weak-panel zone. Key parameters include the axial compression ratio of column and the section depth ratio of beams. Experimental results indicate that four types of failure patterns occurred during the loading process. The
hysteretic loops are stable and plentiful, but have different changing tendency at the positive and negative direction in the later of loading process due to mechanical behaviors of specimens. The ultimate strength tends to increase with the decrease of the section depth ratio of beams, but it is not apparent relationship to the axial compression ratio of column, which is less than 0.5. The top panel zone has good deformation capacity and the shear rotation can reach to 0.04 rad. The top panel zone and the bottom panel zone don`t work as a whole. Based on the experimental results, the equation for shear strength of the abnormal joint panel zone is established by considering the restriction of the bottom panel zone to the top panel zone, which is suitable for the abnormal joint of H-shaped or box column and beams with different depths.
Nonlinear time-varying analysis algorithms for modeling the behavior of complex rigid long-span steel structures during construction processes
Tian, Li-Min ; Hao, Ji-Ping ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1197~1214
DOI : 10.12989/scs.2015.18.5.1197
There is a great difference in mechanical behavior between design model one-time loading and step-by-step construction process. This paper presents practical computational methods for simulating the structural behavior of long-span rigid steel structures during construction processes. It introduces the positioning principle of node rectification for installation which is especially suitable for rigid long-span steel structures. Novel improved nonlinear analytical methods, known as element birth and death of node rectification, are introduced based on several calculating methods, as well as a forward iteration of node rectification method. These methods proposed in this paper can solve the problem of element`s `floating` and can be easily incorporated in commercial finite element software. These proposed methods were eventually implemented in the computer simulation and analysis of the main stadium for the Universiade Sports Center during the construction process. The optimum construction scheme of the structure is determined by the improved algorithm and the computational results matched well with the measured values in the project, thus indicating that the novel nonlinear time-varying analysis approach is effective construction simulation of complex rigid long-span steel structures and provides useful reference for future design and construction.
Adopting flexibility of the end-plate connections in steel moment frames
Ghassemieh, M. ; Baei, M. ; Kari, A. ; Goudarzi, A. ; Laefer, D.F. ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1215~1237
DOI : 10.12989/scs.2015.18.5.1215
The majority of connections in moment resisting frames are considered as being fully-rigid. Consequently, the real behavior of the connection, which has some level of flexibility, is ignored. This may result in inaccurate predictions of structural response. This study investigates the influence of flexibility of the extended end-plate connections in the steel moment frames. This is done at two levels. First, the actual micro-behavior of extended end-plate moment connections is explored with respect to joint flexibility. Then, the macro-behavior of frames with end-plate moment connections is investigated using modal, nonlinear static pushover and incremental dynamic analyses. In all models, the P-Delta effects along with material and geometrical nonlinearities were included in the analyses. Results revealed considerable differences between the behavior of the structural frame with connections modeled as fully-rigid versus those when flexibility was incorporated, specifically difference occurred in the natural periods, strength, and maximum inter-story drift angle.
Simulating the construction process of steel-concrete composite bridges
Wu, Jie ; Frangopol, Dan M. ; Soliman, Mohamed ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1239~1258
DOI : 10.12989/scs.2015.18.5.1239
This paper presents a master-slave constraint method, which may substitute the conventional transformed-section method, to account for the changes in cross-sectional properties of composite members during construction and to investigate the time-dependent performance of steel-concrete composite bridges. The time-dependent effects caused by creep and shrinkage of concrete are considered by combining the age-adjusted effective modulus method and finite element analysis. An efficient computational tool which runs in AutoCAD environment is developed to simulate the construction process of steel-concrete composite bridges. The major highlight of the developed tool consists in a very convenient and user-friendly interface integrated in AutoCAD environment. The accuracy of the proposed method is verified by comparing its results with those provided by using the transformed-section method. Furthermore, the computational efficiency of the developed tool is demonstrated by applying it to a steel-concrete composite bridge.
Behavior and design of perforated steel storage rack columns under axial compression
El Kadi, Bassel ; Kiymaz, G. ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1259~1277
DOI : 10.12989/scs.2015.18.5.1259
The present study is focused on the behavior and design of perforated steel storage rack columns under axial compression. These columns may exhibit different types of behavior and levels of strength owing to their peculiar features including their complex cross-section forms and perforations along the member. In the present codes of practice, the design of these columns is carried out using analytical formulas which are supported by experimental tests described in the relevant code document. Recently proposed analytical approaches are used to estimate the load carrying capacity of axially compressed steel storage rack columns. Experimental and numerical studies were carried out to verify the proposed approaches. The experimental study includes compression tests done on members of different lengths, but of the same cross-section. A comparison between the analytical and the experimental results is presented to identify the accuracy of the recently proposed analytical approaches. The proposed approach includes modifications in the Direct Strength Method to include the effects of perforations (the so-called reduced thickness approach). CUFSM and CUTWP software programs are used to calculate the elastic buckling parameters of the studied members. Results from experimental and analytical studies compared very well. This indicates the validity of the recently proposed approaches for predicting the ultimate strength of steel storage rack columns.
Study on uplift performance of stud connector in steel-concrete composite structures
Ju, Xiaochen ; Zeng, Zhibin ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1279~1290
DOI : 10.12989/scs.2015.18.5.1279
The main role of studs, which act as connectors of the steel-concrete composite structures, is to ensure that the steel and the concrete work together as a whole. The studs in steel-concrete composite structures bear the shearing force in the majority of cases, but in certain locations, such as the mid-span of a simply supported composite beam, the studs bear axial uplift force. The previous studies mainly focused on the shearing performance of the stud by some experimental and theoretical effort. However, rare studies involved the uplift performance of studs. In this paper, the single stud uplift test on 10 composite specimens was performed. Meanwhile, based on the test, numerical analysis was introduced to simulate the concrete damage process due to the stud uplifted from concrete. The static ultimate bearing capacity, under which the stud connector was pulled out from the damaged reinforced concrete, is much larger than the cyclic ultimate bearing capacity, under which the weld joint between stud and steel plate fractured. According to the fatigue test results of 7 specimens, the fatigue S-N curve of the construction detail after minus 2 times standard deviation is $logN
A study on different failure criteria to predict damage in glass/polyester composite beams under low velocity impact
Aghaei, Manizheh ; Forouzan, Mohammad R. ; Nikforouz, Mehdi ; Shahabi, Elham ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1291~1303
DOI : 10.12989/scs.2015.18.5.1291
Damage caused by low velocity impact is so dangerous in composites because although in most cases it is not visible to the eye, it can greatly reduce the strength of the composite material. In this paper, damage development in U-section glass/polyester pultruded beams subjected to low velocity impact was considered. Different failure criteria such as Maximum stress, Maximum strain, Hou, Hashin and the combination of Maximum strain criteria for fiber failure and Hou criteria for matrix failure were programmed and implemented in ABAQUS software via a user subroutine VUMAT. A suitable degradation model was also considered for reducing material constants due to damage. Experimental tests, which performed to validate numerical results, showed that Hashin and Hou failure criteria have better accuracy in predicting force-time history than the other three criteria. However, maximum stress and Hashin failure criteria had the best prediction for damage area, in comparison with the other three criteria. Finally in order to compare numerical model with the experimental results in terms of extent of damage, bending test was performed after impact and the behavior of the beam was considered.
A component method model for blind-bolts with headed anchors in tension
Pitrakkos, Theodoros ; Tizani, Walid ;
Steel and Composite Structures, volume 18, issue 5, 2015, Pages 1305~1330
DOI : 10.12989/scs.2015.18.5.1305
The successful application of the component-based approach - widely used to model structural joints - requires knowledge of the mechanical properties of the constitutive joint components, including an appropriate assembly procedure to derive the joint properties. This paper presents a component-method model for a structural joint component that is located in the tension zone of blind-bolted connections to concrete-filled tubular steel profiles. The model relates to the response of blind-bolts with headed anchors under monotonic loading, and the blind-bolt is termed the "Extended Hollo-bolt". Experimental data is used to develop the model, with the data being collected in a manner such that constitutive models were characterised for the principal elements which contribute to the global deformability of the connector. The model, based on a system of spring elements, incorporates pre-load and deformation from various parts of the blind-bolt: (i) the internal bolt elongation; (ii) the connector`s expanding sleeves element; and (iii) the connector`s mechanical anchorage element. The characteristics of these elements are determined on the basis of piecewise functions, accounting for basic geometrical and mechanical properties such as the strength of the concrete applied to the tube, the connection clamping length, and the size and class of the blind-bolt`s internal bolt. An assembly process is then detailed to establish the model for the elastic and inelastic behaviour of the component. Comparisons of model predictions with experimental data show that the proposed model can predict with sufficient accuracy the response of the component. The model furthers the development of a full and detailed design method for an original connection technology.