Behavior of Steel Beam to Reinforced Concrete Column Connections

Transcription

1 Canadian Journal of Basic and Applied Sciences PEARL publication, 215 CJBAS Vol. 3(12), , December 215 ISSN Behavior of Steel Beam to Reinforced Concrete Column Connections Mohammad Hossein Naseri Fard, Saeed Pirooz Bakht, Mohamad Ali Dashti Rahmat Abadi Department of Civil Engineering, Yazd branch, Islamic Azad University, Yazd, Iran. Keywords: Steel Beam-Concrete Column composite connection, Finite Element Model, Strength, Concrete Connection, Steel Connection Abstract Composite structures with combination of steel and reinforce concrete has been widely used over 3 decades all over the word. connection between steel and RC columns is the most critical part mention composite and caused the scholars do more investigation on this part. aim of this research is to consider the bending connection of steel beam to RC column as a critical part. ABAQUS software has been employed to numerically simulate these members and parametrically discuss the performance of this part. result of this study shows the effectiveness se parameters on the behavior se types of connections and cracking patterns. 1. Introduction Composite structures with combination of steel and reinforce concrete has been widely used over 3 decades all over the word. connection between steel and RC columns is the most critical part of the mention composite and caused the scholars do more investigation on this part. Reinforced concrete columns and steel beams (RCS) optimize the connection steel and concrete elements, reduce the cost and enhance in the structural damping. So many investigations has been done to study the behavior of RCS since Sheikh [1]; and many studies objectives was to find new through-column-type joint to optimize path while these joint has been covered by vertical steel plate which has been called through plate [2-5]. re are also so many finite element models to study the behavior se kinds of junctions [6-9]. American Society of Civil Engineering ASCE had proposed a design equation which prepared a new guideline for designers for design of joints between steel beam and RC columns [1] 2. Material and Methods Various experiments on beam-column connections have indicated that various parameters affect the determination shear capacity of connection. However, the behavior of beam-column connection is very complex and a comprehensive test will not be able to cover all combinations of Corresponding Author.

2 these variables. As a result, the non-linear finite element analysis se connections can provide a powerful means for modeling and designing of various parameters influencing the behavior of beam-column connection. In this section, the effect of various parameters such as the amount of axial, the applied axial (the effect of eccentricity), steel cover plate thickness, steel cover plate height, the effect of change in compressive of concrete and the effect of change in resistance of steel have been investigated. In the surveys conducted, the enters the connection as the over by changing the same place. This method of ing is a simple and practical method which can be used for long-term effects applied s. In each section, the studies conducted on a parameter in the connection have been presented and the impact of changing that parameter has been concluded. 2.1 effect of axial In this section, the effect axial available before making a lateral on the connection has been investigated. ratio studied axial in this section has been considered to be.1,.4 and.7 intended column pressure capacity ' ' ' (.1 Ag fc kn.4 Ag fc kn.7 Ag fc kn) , According to Figure 1, the diagonal cracks expansion within the connection s through increasing the amount of axial. number, the depth and the growth of cracks within the connection are accumulated. se cracks have less expansion to area under the connection in the column. It can be said that the d axial makes the deterioration to move from the column to the connection. By increasing the axial and creating the confinement inside the steel cover plate and panel zone, the formation of tensile cracks has been delayed. P=.1 A g F c P=.4 A g F c P=.7 A g F c Figure 1. pattern of concrete column cracking with changing the axial 34

3 Load(KN) P=.7 A g F c P=.4 A g F c Figure 2. distribution of minimum pricipal stresses in the steel beam at the connection P=.1 A g F c p=.44agfc p=.1agfc p=.4agfc p=.7agfc Displacement (mm) Figure 3. Load-displacement curve for the effect of axial According to Figure 3, by increasing the amount of axial, the initial s in the first part curve. In the axial of.1 column pressure capacity which is about 2.28 times the initial, the general trend diagram is fixed. It shows that this had little effect on connection capacity. By increasing the axial to.4 column pressure capacity, the connection capacity to displacement s about 8 mm which is about 1% of.1 axial s. By increasing the axial to.7 column pressure capacity, the connection capacity to displacement s about 65 mm which is about 15-2 % of.1 axial s column pressure capacity. reason for this behavior can be the column axial measures to prevent the connection cracks from opening the same as post-tensioning. Resulting from the displacement of about 8 mm, the slope curve is changed due to the in P-Δ effectiveness and reduced 341

4 This indicates that, in the great axial s, the sustainable moment increasing by beam cross after the point is less than the increasing amount of moment caused by P-Δ. If the lateral is applied to the structure as the force control, the structure failure will be brittle. initial of connection s for 4, 2 and 36%, respectively in s of.1,.4 and.7 compared to the initial samples with s of.44. increasing amount in these examples is 1, 9 and 12, respectively. slope of all four samples is almost equal after the displacement of about 8 mm. final first three samples was equal. It has become less than 3% initial in the with the.7 coefficient column pressure capacity. It indicates the in the ultimate of large axial s. Table 1. Hardness, and ultimate of RCS complex connection for axial effect amount of vertical (KN).44 A g F c.1 A g F c.4 A g F c.7 A g F c Load coefficient value of (KN/mm 2 ) of 4% 2% 36% % 9% 12% Ultimate ultimate -2.4% Plasticity ( u/ y) It can be concluded that the of axial force with medium and high doses will the samples'. In axial of.1 to.4 column pressure capacity, the amount ultimate shear connection is optimal. After that, with the in axial, the amount of ultimate shear reduces effect of eccentricity In the reference (primary) sample, the location of applying the axial on the column is located exactly in the center column section. In this section, the effect of eccentricity axial with the sizes of.5 after the column (32.5 = 65.5 mm),.1 after the column (65 = 65.1 mm) and.15 after the column (97.5 = mm) and.25 after the column (162.5 = mm) will be investigated. According to Figure 4, there has been little change in the crack pattern on the concrete column by changing the eccentricity. 342

5 Load(KN) Ex,Ey=.5 h c Ex,Ey=.1 h c Ex,Ey=.15 h c Ex,Ey=.25 h c Figure 4. crack pattern on the concrete column against the changing eccentricities Displacement(mm) Ex,Ey= Ex,Ey=.5h c Ex,Ey=.1hc Figure 5. -displacement curve for the effect of eccentricity of axial According to the diagram, by increasing the eccentricity axial applied on the column, the connection capacity correspondingly reduces due to the formation of moment. initial of samples decreases 6, 12, 13 and 15%, respectively. In eccentricity of.5 after the column, the ultimate connection decreases about 1%. In eccentricities of.1 and.15 after the column, the ultimate capacity connection decreases about 2 and 3%, respectively. In eccentricity of.25, the connection decreases about 5%. connection decreases about 1, 3, 4, and 6%, respectively. 343

6 Table 2. Hardness, and ultimate of RCS complex connection for the effect of eccentricity amount of axial eccentricity, )mm).3h c.1h c.13h c.53h c Eccentricity coefficient value of (KN/mm 2 ) of -6% -12% -13% -15% % -2% -4% -6% Ultimate ultimate -1% -2% -3% -5% Plasticity ( u/ y) It can be concluded that the of eccentricity up to.15 after the column does not have a significant effect on the bearing capacity connection. eccentricities of.25 and higher reduce the final and the initial connection correspondingly. With the of axial eccentricity compared to the center column cross-section, the connection resistance reduces against the applied due to the created moment. ultimate resistance in the displacement curve decreases. It can be expected that, with the axial eccentricity, the connection (the slope -displacement curve) decreases. reason for this can be attributed to the moment which creates the eccentricity. this moment reduce the connection resistance. 3. Conclusion Increasing axial makes the deterioration to move from the column to the connection. By increasing the axial and creating the confinement inside the steel cover plate and panel zone, the formation of tensile cracks has been delayed. It can be expected that, with the axial eccentricity, the connection (the slope -displacement curve) decreases. reason for this can be attributed to the moment which creates the eccentricity. moment plays the role connection resistance reducer. In eccentricities of.1 and.15 after the column, the ultimate capacity connection decreases about 2 and 3%, respectively. In eccentricity of.25, the connection decreases about 5%. connection decreases about 1, 3, 4, and 6%, respectively. In the great axial s, the sustainable moment increasing by beam cross after the point is less than the increasing amount of moment caused by P-Δ. If the lateral is applied to the structure as the force control, the structure failure will be brittle. References [1] Sheikh, T.M., Deierlein, G.G., Yura, J.A. and Jirsa, J.O.: Beam-column moment connections for composite frames: Part 1, Journal of structural Engineering, ASCE, 115(11), , (1989). [2] Baba N. and Nishimura Y.: Stress transfer on through beam type steel beam- reinforced concrete column joints, Proceedings of 6th ASCCS conference, 753 6, ( 2). 344

7 [3] Bugeja MN., Bracci JM. and Moore WP.: Seismic behavior of composite RCS frame systems, Journal of Structural Engineering, ASCE 2, 126(4), , (2). [4] Cheng, C.T. and Chen, C.C.: Seismic behavior of steel beam and reinforced concrete column connections, Journal of Constructional Steel Research, 61, , (25) [5] Deierlein, G.G., Sheikh, T.M., Yura, J.A., and Jirsa, J.O.: Beam-column moment connections for composite frames: Part 2, Journal of structural Engineering, ASCE, 115(11), , (1989). [6] Eurocode-2.: Design of Concrete Structures, Part 1: General Rules and Rules for Building, ENV ,(1992). [7] Hibbitt, K. and Sorensen.: ABAQUS, Standard user's manual, Version 6.1, USA. Kim K. and Noguchi H. (1997), An analytical study on the shear of RCS joints, 4th JTCC meeting, (21). [8] Nishiyama I., Itadani H. and Sugihiro K.: 3D beam column connection (joint panel) tests on RCS, 4th JTCC meeting, (1997). [9] Parra-Montesinos G. and Wight JK.: Seismic response of exterior RC column- to-steel beam connections, Journal of Structural Engineering, ASCE 2, 126(1), , (2). [1] ASCE.: Guidelines for design of joints between steel beams and reinforced concrete Columns, Journal of structural Engineering, ASCE, 12(8), , (1994). 345