This paper shows the results of modeling two cases of the steel-concrete composite beam: one with single-I steel and another with double-I steel. Both cases have the same steel area. Abaqus software was used to simulate and compare the results between 2 cases in terms of bearing capacity, displacement, stress/force and failure mode.
Tuyển tập Hội nghị Khoa học thường niên năm 2017 ISBN: 978-604-82-2548-3 COMPARISON OF A STRUCTURAL BEHAVIOUR BETWEEN COMPOSITE SINGLE-I ENCASED STEEL BEAM AND A DOUBLE-I ENCASED STEEL COMPOSITE BEAM Nghiem Tien Dung1 , Vu Thi Thu Thuy2 School of International Education, Thuyloi University, email: dungnt5nk1@wru.vn Civil Engineering faculty, Thuyloi University INTRODUCTION Nowadays, the steel-concrete composite is an advantageous solution that has been widely used in many countries in the world for multi-storied buildings There have been many studies on this subject throughout the world Books of Nethercot, 2003; Johnson, 2004; Pham, 2006; or the standards Eurocode and AISC 2010, 2016 had published design instructions for composite structures with single encased steel profile However, there are no design standard guidelines for steelconcrete composite with multiple encased steel profiles Meanwhile, several international and domestic researchers have published on steel-concrete composite structures with multiple encased steel profiles using physical and numerical models Zhou et al., 2010 presented experimental and numerical studies of the composite shear wall with multi-embedded steel sections They indicated that composite shear walls with multi-embedded steel sections have better energy dissipation capacity than that with a single one The presence of multi embedded steel sections did not affect the final failure mode of the composite shear walls, but they would restrain the development of cracks and prevent the concrete from severe spalling Tran, 2015 performed his experimental results on the behavior of composite concrete beams with H-steel profiles He also provided some suggestions on model design for this type of beam based on the results Tran and Vu, 2016 used Abaqus software to model the steel-concrete composite beams with H-encased steel profiles and compare the numerical results with Tran’s experimental results However, until now there has been no study on the comparison of behavior between composite beams with single I-encased steel versus multiple Iencased steel This paper shows the results of modeling two cases of the steel-concrete composite beam: one with single-I steel and another with double-I steel Both cases have the same steel area Abaqus software was used to simulate and compare the results between cases in terms of bearing capacity, displacement, stress/force and failure mode ABAQUS AND SET UP MODEL Abaqus is one of the popular software for structural analysis based on the finite element method Abaqus offers a wide range of options for describing element types separately, then assemble them to a 3D completed object Particularly, different material models with many stages can be described in detail using Abaqus Also, the appropriate results between the numerical model and experiments of Tran and Vu, 2016 show that Abaqus is a useful tool to model cases of this research Simply supported beam under bending is selected for this research as Figure 586 Tuyển tập Hội nghị Khoa học thường niên năm 2018 ISBN: 978-604-82-2548-3 are nonlinear The parameters of I-encased steel S355, longitudinal steel bars, and stirrup are presented in Table In which f y is yield strength, fu is ultimate strength, and Es is the modulus of elasticity of reinforcing steel Solid element type (C3D8R) with nodes were selected for concrete beam and encased Figure Structural sketch of research steel sections, the overall size of 50mm steel-concrete composite beams T3D2 truss type elements with nodes were The calculated length of the composite used for reinforcement bars 12 and 20 beams is Lo=10m Beam’s true length because they only have axial forces, size of L=11m Center of supports is 0.5m away 25mm The connection between bars 20, from the beam’s edges Cross section 12 and the surrounding concrete is perfect, dimension is chosen as b=35cm and h=55cm, hence “embedded” was used Bonding between encased steel surfaces and with the ratio Lo/h=18 and h/b=1.57 Two cases for modeling and comparison surrounding concrete is not perfect Thus, the surface-to-surface interaction model was used are shown in Figure 1) Table Steel parameters 2) Steel type IPE S355 120 220 160 20 fy (MPa) 355 365 fu (MPa) 380 390 Es (GPa) 210 200 12 290 310 200 To efficiently control the failure of composite beam, the applied load acting on Both cases have a similar total area of I the beam was replaced with the displacement encased steel of 33.3 cm2 The shape and of up to 100mm downwards, at point A (see dimension of the ‘I’ encased steel is applied Figure 1) Each case is carried out in 300 according to the European standards Other steps of displacement increasing reinforced steels that are chosen for both cases: stirrup 12 (1.13 cm2 ) and RESULTS AND COMPARISON longitudinal steel bars 20 (3.14cm2 ) at the Figure shows the relationship between corners of the stirrup (Figure 2) with a 5cm protection concrete layer The second case applied load F and vertical displacement at was chosen based on the results of Vu’s point A of both cases It clearly shows research It shows that with the same area of I stages of the loading process steel, the composite beam with encased I in horizontal position; the smaller one in compression zone and the bigger one in tension zone has the largest bearing capacity Selected materials are as follows: C30 for the concrete according to Eurocode with characteristic compressive cylinder strength of concrete at 28 days fck =30MPa, mean value of axial tensile strength of concrete Figure The relation between applied load fctm=2.9MPa, material models used in Abaqus F and displacement at point A (F~UA ) Figure Cross sections of two cases 587 Tuyển tập Hội nghị Khoa học thường niên năm 2017 ISBN: 978-604-82-2548-3 - Stage 1: applied load F 150kN and displacement at A UA 27mm, both cases work similarly with lines coincide with each other - Stage 2: 150kN F 215kN and 27mm UA 53mm, the double I beam works better a little bit compared to the single I beam During these above stages, the development of Von Mises stress in concrete compression zone and I steel tension zone of both cases are the same as shown in Figure and Figure - Stage 3: F> 215kN, the single I beam performs better bearing capacity corresponding to above dash line and reaches the limit stage lately around 235kN with a displacement of UA beyond 60-70mm ( Figure 3) Whereas, the double I beam reaches the limit stage earlier at 215kN and stable at that value during the displacement at A is rising During this stage, both concrete’s compression zone and I steel’s tension zone reach their strength at the same displacement of 50mm corresponding to compressive strength of 30MPa (Figure 4) and yield strength of 355MPa relatively (Figure 5) single I beam in the middle zone and the supported area corresponding more red dots Figure Images of tensile f ailure of both cases under the same load F=215kN CONCLUSION Results of modeling by Abaqus and comparison between two composite beams indicate that at the limit stage, the composite beam with single-I performs larger bearing capacity and less failure compared to the beam with double-I In this situation, the longitudinal steel bars 20 reinforced for both cases seem to be large so that they can bear a compressive load together with a compressive zone of concrete Therefore the bearing capability of upper I steel in double-I beam has not yet completely made use There would be more tests to be done for a general conclusion REFERENCE Figure The relation between Mises stress of concrete’s compression zone and UA Figure The relation between Mises stress of I steel’s tension zone and UA Figure shows the images of tensile failure of half beam for both cases under the same load F=215kN As can be seen, the double I beam has a severe failure than the [1] Eurocode 4, 2005: Design of composite steel and concrete structures Part 1.1: General rules and rules for buildings [2] Pham V Hoi, 2006 Kết cấu liên hợp thép bêtông dùng strong nhà cao tầng NXB Khoa học kỹ thuật, Hà Nội [3] Tran V Toan, 2015 Experimental and numerical study of composite steel-concrete walls with several fully encas ed steel profiles Ph.D Thesis, France [4] Tran V Toan and Vu T T Thuy, 2016 Nghiên cứu dự làm việc dầm bê tông cốt thép cứng khơng có kết nối bề mặt thép hình bê tơng chịu uốn đơn mơ hình số Tạp chí Tài nguyên nước - Hội Thủy lợi Việt Nam, vol 03 [5] Y Zhou, X Lu, Y Dong, the Seismic behaviour of composite shear walls with multi embedded steel sections Part I: experiment, Struct Design Tall Spec Build 19 (6) (2010) 618–636 588 ... the failure of composite beam, the applied load acting on Both cases have a similar total area of I the beam was replaced with the displacement encased steel of 33.3 cm2 The shape and of up... days fck =30MPa, mean value of axial tensile strength of concrete Figure The relation between applied load fctm=2.9MPa, material models used in Abaqus F and displacement at point A (F~UA ) Figure... of both cases under the same load F=215kN CONCLUSION Results of modeling by Abaqus and comparison between two composite beams indicate that at the limit stage, the composite beam with single-I