Prediction of the flexural overstrength factor for steel beams using artificial neural network

Esra Mete Güneyisi,Mario D’Aniello,Raffaele Landolfo,Kasım Mermerdaş 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.3

The flexural behaviour of steel beams significantly affects the structural performance of the steel frame structures. In particular, the flexural overstrength (namely the ratio between the maximum bending moment and the plastic bending strength) that steel beams may experience is the key parameter affecting the seismic design of non-dissipative members in moment resisting frames. The aim of this study is to present a new formulation of flexural overstrength factor for steel beams by means of artificial neural network (NN). To achieve this purpose, a total of 141 experimental data samples from available literature have been collected in order to cover different cross-sectional typologies, namely I-H sections, rectangular and square hollow sections (RHS-SHS). Thus, two different data sets for I-H and RHS-SHS steel beams were formed. Nine critical prediction parameters were selected for the former while eight parameters were considered for the latter. These input variables used for the development of the prediction models are representative of the geometric properties of the sections, the mechanical properties of the material and the shear length of the steel beams. The prediction performance of the proposed NN model was also compared with the results obtained using an existing formulation derived from the gene expression modeling. The analysis of the results indicated that the proposed formulation provided a more reliable and accurate prediction capability of beam overstrength.

Ultimate Capacity Prediction of Axially Loaded CFST Short Columns

Esra Mete Güneyisi,Ayşegül Gültekin,Kasım Mermerdaş 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.1

Composite columns have superior strength and ductility performance, and they have become more widely accepted in the engineering applications. However, the filled tubular columns require more attention. This study aims to present a new formulation for the axial load carrying capacity ( Nu ) of circular concrete filled steel tubular (CFST) short columns having various geometrical and material properties. Although there have been some empirical relations for predicting Nu in the literature, genetic algorithm based explicit formulation is not available. In the current study, 314 comprehensive experimental data samples presented in the previous studies were examined to prepare a data set for training and testing of the prediction model. The prediction parameters were selected as outer diameter of column (D), wall thickness ( t ), length of column ( L ), compressive strength of concrete ( fc ), and yield strength of steel ( fy ). The prediction model was obtained by means of gene expression programming (GEP). The proposed model was compared with available ones presented in the current design codes (ACI, Australian Standards, AISC, AIJ, Eurocode 4, DL/T, and CISC) and some existing empirical models proposed by researchers. The prediction performance of all models were also evaluated by the statistical parameters. The results indicated that the GEP model was much better than the available formulae, yielding higher correlation coefficient and lower error

Nonlinear analysis of concrete-filled single and double skin steel tubular tapered columns under axial loading

Süleyman İpek,Esra Mete Güneyisi 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.4

In this study, the structural response of concrete-filled single and double skin steel tubular (CFST and CFDST) composite tapered columns was investigated through the finite element method (FEM). In the development of the FEM model, the concentric axial loading condition and circular section were adopted. Experimental results available in the literature were used to verify the proposed FEM model. In addition, a parametric study was performed to visualize the effectiveness of tapered angle and material strengths on the ultimate capacity of CFST and CFDST tapered columns. To this aim, a total of 60 tapered column samples (including 30 CFST and 30 CFDST columns) were modeled by taking into consideration five tapered angles, two steel tube yield strengths, and three concrete cube compressive strengths. The verification of the FEM model revealed that the developed model has a reliable and trustable assessment capability. It was noticed that the tapered angle was the most crucial parameter, influencing significantly the ultimate axial strength and stiffness of both CFST and CFDST composite tapered columns. As well, it was overtly beheld from the study that CFST composite tapered column specimens had better ultimate axial strength values than CFDST composite tapered column specimens with the same sectional and material properties.

Combined Effect of Bearing Stiffness of the Base Isolator and Damping Characteristics of the Viscous Damper on the Nonlinear Response of Buildings

Ahmet Hilmi Deringöl,Esra Mete Güneyisi,Osman Hansu 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.5

Recently, the base isolation system (BIS) has been adopted as mature structural protective system which dissipates the most part of the input energy emerged during any type of seismic excitation. However, BIS can induce large displacement because of having easily movement tendency of the bearing. Therefore, this study proposes a set of BIS incorporated with supplementary damping device to control the nonlinear response of the buildings with low and moderate heights. For this, 5 and 10-storey steel moment resisting frames isolated with lead rubber bearing (LRB) with varying stiff ness properties (i.e. high, moderate, and low) were studied. Afterwards, viscous damper (VD) was designed with three diff erent damping exponents of 0.3, 0.6, and 1.0 so that they were alternatively distributed both in inner and corner bays throughout the building heights. The eff ectiveness of the proposed isolation models with and without VDs were evaluated through the nonlinear time history analyses under diff erent earthquake records. Advantages of the developed isolation systems over both the fi xed base and the base isolated frames were discussed in terms of the storey, bearing, and relative displacements, roof and interstorey drift ratios, absolute acceleration, base shear, and hysteretic curves. It was shown that low-stiff ness-LRB (LLRB) associated with the VD of proper damping exponent and implementation layout signifi cantly mitigated the structural response of the buildings.

Effect of Using High Damping Rubber Bearings for Seismic Isolation of the Buildings

Ahmet Hilmi Deringöl,Esra Mete Güneyisi 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.5

In this study, the use of high damping rubber bearing (HDRB) with various design properties in mitigating the seismic eff ects for steel buildings was investigated. For this, a generalized demand on the analytical model of HDRB was introduced and eighteen diff erent models of HDRB were examined comparatively. These models were created by considering three signifi cant isolation parameters of HDRB such as isolation period T (2, 2.5, and 3 s), eff ective damping ratio β (0.05, 0.10, 0.15), and post-yield stiff ness ratio λ (3 and 6). The benchmark low (3-storey), mid (6-storey), and high-rise (9-storey) steel buildings were equipped with diff erent isolation systems of HDRB and then subjected to a set of earthquake ground motions through nonlinear time history analyses in order to evaluate the actual nonlinear behaviour of the bearings in the base-isolated steel buildings in service. The base-isolated frames were assessed by the variation of the selected structural response parameters such as isolator displacement, relative displacement, inter-storey drift ratio, absolute acceleration, base shear, hysteretic curve, and dissipated energy. The eff ectiveness of the isolation parameters on the nonlinear response of the steel buildings with HDRB under earthquakes was comparatively evaluated to generate alternatively innovative isolation system. It was shown that the seismic performance of the base-isolated structure was remarkably infl uenced by the isolation parameters. The most favourable base isolation model was obtained when the higher value of the isolation period and eff ective damping ratio combined with the low post-yield stiff ness ratio.

An artificial intelligence-based design model for circular CFST stub columns under axial load

Süleyman İpek,Ayşegül Erdoğa,Esra Mete Güneyisi 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.1

This paper aims to use the artificial intelligence approach to develop a new model for predicting the ultimate axial strength of the circular concrete-filled steel tubular (CFST) stub columns. For this, the results of 314 experimentally tested circular CFST stub columns were employed in the generation of the design model. Since the influence of the column diameter, steel tube thickness, concrete compressive strength, steel tube yield strength, and column length on the ultimate axial strengths of columns were investigated in these experimental studies, here, in the development of the design model, these variables were taken into account as input parameters. The model was developed using the backpropagation algorithm named Bayesian Regularization. The accuracy, reliability, and consistency of the developed model were evaluated statistically, and also the design formulae given in the codes (EC4, ACI, AS, AIJ, and AISC) and the previous empirical formulations proposed by other researchers were used for the validation and comparison purposes. Based on this evaluation, it can be expressed that the developed design model has a strong and reliable prediction performance with a considerably high coefficient of determination (R-squared) value of 0.9994 and a low average percent error of 4.61. Besides, the sensitivity of the developed model was also monitored in terms of dimensional properties of columns and mechanical characteristics of materials. As a consequence, it can be stated that for the design of the ultimate axial capacity of the circular CFST stub columns, a novel artificial intelligence-based design model with a good and robust prediction performance was proposed herein.