An Investigation of Base Plate Connections of a Steel Industrial Building Having Different Column Cross-Sections

NESciences, 2019, 4(2): 84-91 - RESEARCH ARTICLE An Investigation of Base Plate Connections of a Steel Industrial Building Having Different Column Cross-Sections Pinar Salahaldin Hussein Hussein1, Günnur Yavuz2 1 2 Department of Civil Engineering, Kirkuk University, Kirkuk, Iraq Department of Civil Engineering, Konya Technical University, Konya, Turkey Abstract In this study, steel column base plate connections of a steel industrial building that are one of the most important connection regions were studied. Two dimensional static analysis of a steel industrial building was performed and exposed column base plate dimensions were determined according to American Institute of Steel Construction Code-LRFD (Load and Resistance Factor Design) method. The effects of selected steel column cross section types on the behaviour of column base plate connections were investigated by using RFEM finite element analysis program. For this purpose, finite element analysis of three types of column base plate connection models were performed and evaluated comparatively. From results, the best value for top column lateral displacement was obtained in W column section-base plate connection and the best behaviour for Von Mises stresses values was obtained in square hollow section column. The undesired behaviour was determined in circular hollow section column-base plate connection type. Keywords: Industrial building, Column, Base plate, Finite element analysis, LRFD. Article history: Received 01 November 2018, Accepted 29 March 2019, Available online 16 May 2019 Introduction The column base plate connections are one of the most important regions of steel structures. The typical column base plate connection consists of steel column, base plate, anchor bolts, grout and concrete foundation. The column base plates transfer axial loads, moments, tension and shear forces from building to concrete foundation and it may be designed with special parts to sufficiently  Corresponding Author: Günnur YAVUZ, e-mail: Natural and Engineering Sciences 85 loads transfers and to increase its strength. The column base plate types used in steel structures are exposed and embedded base plates. The exposed base plate connection is used in both seismic and non-seismic regions (Kingsley, 2005). The exposed column base plate connection consists of a steel column welded to a base plate and anchor bolts. The base plate is bolted by anchor bolts to a concrete pedestal or foundation. This connection type, are withstand the moment and axial loads through the bearing on the foundation in compression and tension in the anchor rods. Also these connections are withstand the shear forces through the shear in the anchor rods and friction between the base plate and foundation (Kingsley, 2005). Exposed column base plate connection is one of the most important connection types in a steel structure, especially in a steel Moment Resisting Frame (MRF). In a MRF, base plate connects the column to the concrete foundation directly therefore lateral forces that form of wind or seismic effects can be transferred through the base plate and anchor bolts to the grout layer and concrete foundation (Lee et. al., 2008). In the past, the best way of studying the behaviour of column base plate connections was testing experimental models. Although the results of such experiments are closer to reality, their cost is expensive. Additionally, in order to understand the behaviour of connections with different models, these experiments should be repeated several times. Therefore, understanding the behaviour of different types of base plates, failure modes and their advantages and disadvantages by using computer simulations can result in great savings. The relation between experimental and analytical model of column base plates was shown in many studies. Most of these investigations were on simple base plates without stiffeners and the verification among results seemed to be satisfactory (Shafieifar & Khonsari, 2012, Stamatopulos & Ermopoulos, 2011). Until one of the failure modes of column base plate connection such as formation of a plastic hinge in the column, a plastic mechanism in the base plate, crushing of concrete in bearing, yielding of the anchor bolts in tension, or tear off of the concrete by the anchor bolts in tension was not effective, the general behaviour of a column base plate connection will be elastic (Roşca et. al., 2013). In this study, nonlinear finite element analysis for a single story steel industrial building with exposed column base plate connections having different column types were performed. The support reactions which obtained from two dimensional analysis for the building were used to determine the base plate dimensions according to American Institute of Steel Construction (AISC)Guide 1, Load and Resistance Factor Design (LRFD) method. Then the base plate and anchor bolts details were used in different models with W, square hollow and circular hollow column crosssections. The finite element analysis of these types of steel column base plate connections were performed and evaluated comparatively. Materials and Methods Single story steel industrial building The column and beam sections were selected as W18x119 (depth d=18.97 in (482 mm), flange width bf =11.265 in (286 mm)) in the industrial building (Figure 1). Steel material was selected as Grade 36, for this material yield stress Fy equals to 36 ksi (244.8 MPa) and concrete compressive strength fc' equal to 4 ksi (27.2 MPa). The dead, snow and wind loads were applied on the frame in two dimensional analysis of the industrial building. Natural and Engineering Sciences 86 Figure 1. Load values applied on industrial building (a) dead and snow loads, (b) wind loads. Two dimensional analysis of the industrial building having fixed supports was performed in SAP2000 program and the support reactions were obtained according to LRFD load combinations. The support reactions were used to determine the base plate dimensions and anchor bolt details according to AISC-Design Guide 1. The maximum support reactions which obtained from (1.2D+1.6S+0.8W) load combination were Mu= -2350.279 kip.in (-265.55 kN.m), Pu= 39.076 kip (173.82 kN) and Vu= -22.136 kip (-98.466 kN). According to AISC Base Plate and Anchor Rod Design Guide 1- LRFD method, if equivalent eccentricity greater than critical eccentricity which calculated as shown in Table 1, the column base plate will be under large moment effect, so the design procedure for large moment case was used to evaluate the base plate dimensions. The base plate dimensions (NxB) and plate thickness were determined as 30x25 in (762x635 mm) and 2 in (50.8 mm), respectively. 6 pieces 1 1/4 in (31.75 mm) diameter bolts were used according to AISC Steel Design Guide 1-Table 2.3 (Yavuz & Hussein, 2015). The applied design procedure for the base plate under large moment effect is presented in Table 1. Table 1. Design procedure for base (...truncated)