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Volume 45, Number 2, October25 2022

This paper proposes a hybrid machine-learning model, which is called DANN-IP, that combines a deep artificial neural network (DANN) and an interior-point (IP) algorithm in order to improve the prediction capacity on the patch loading resistance of steel plate girders. For this purpose, 394 steel plate girders that were subjected to patch loading were tested in order to construct the DANN-IP model. Firstly, several DANN models were developed in order to establish the relationship between the patch loading resistance and the web panel length, the web height, the web thickness, the flange width, the flange thickness, the applied load length, the web yield strength, and the flange yield strength of steel plate girders. Accordingly, the best DANN model was chosen based on three performance indices, which included the Rˆ2, RMSE, and a20-index. The IP algorithm was then adopted to optimize the weights and biases of the DANN model in order to establish the hybrid DANN-IP model. The results obtained from the proposed DANN-IP model were compared with of the results from the DANN model and the existing empirical formulas. The comparison showed that the proposed DANN-IP model achieved the best accuracy with an Rˆ2 of 0.996, an RMSE of 23.260 kN, and an a20-index of 0.891. Finally, a Graphical User Interface (GUI) tool was developed in order to effectively use the proposed DANN-IP model for practical applications.

Key Words
artificial neural network; interior-point algorithm; machine learning; patch loading resistance; steel plate girder

Sy Hung Mai and Viet Tiep Nguyen:Department of Hydraulic Engineering and Construction, Hanoi University of Civil Engineering (HUCE), Hanoi, Vietnam

Viet-Linh Tran and Duy-Duan Nguyen:Department of Civil Engineering, Vinh University, Vinh 461010, Vietna

A review of previous studies shows that although there is a considerable difference between buckling loads of structures under follower and non-follower lateral loads, only the buckling load of FGM elliptical cylindrical shell under nonfollower lateral load was investigated in the literature. This study is the first to obtain the buckling load of elliptical FGM cylindrical shells under follower lateral load and also make a comparison between buckling loads of elliptical FGM cylindrical shells under follower and non-follower lateral loads. Moreover, this research is the first one to derive the load potential function of elliptical cylindrical shell. In this regard, the FGM cylindrical elliptical shell was modeled using the semi-analytical finite strip method and based on the First Shear Deformation Theory (FSDT). The shell is discretized by strip elements aligned in the longitudinal direction. The Lagrangian and harmonic shape functions were considered in the circumference and longitudinal directions, respectively. The buckling pressure of the shell under follower and non-follower lateral loads was obtained from eigenvalue problem. The results obtained from the model were compared with those presented in the literature to evaluate the validity of the model. A comparison index was defined to compare the buckling loads of the shell under follower and nonfollower lateral load. A parametric study was carried out to investigate the effects of material properties and shell geometry characteristics on the comparison index. For the elliptical cylindrical shells with length-to-radius ratio greater than 16 and majorto-minor axis ratio greater than 0.6, the comparison index reaches to more than 20 percent which is significant. Moreover, the maximum difference is about 30 percent in some cases. The results obtained from the parametric study indicate that the buckling load of long elliptical cylindrical shell under non-follower load is not reliable.

Key Words
buckling; elliptical cylindrical shell; FGM; follower load; FSDT; lateral load

Alireza Moradi, Davood Poorveis and Amin Khajehdezfuly:
Faculty of Civil Engineering and Architecture, Shahid Chamran University of Ahvaz, Ahvaz, Iran

The need for establishing the contribution of pultruded FRP encasements and additional FRP wraps around these encasements to the shear strength and load-deflection behavior of reinforced concrete beams is the main motivation of the present study. This paper primarily focuses on the effect of additional wrapping around the composite beam on the flexural and shear behavior of the pultruded GFRP (Glass Fiber Reinforced Polymer) beams infilled with reinforced concrete, taking into account different types of failure according to av/H ratio (arch action, shear-tension, shear-compression and pure bending). For this purpose, nine hybrid beams with variable shear span-to-depth ratio (av/H) were tested. Hybrid beams with 500 mm, 1000 mm, and 1500 mm lengths and cross-sections of 150x100 mm and 100x100 mm were tested under three-point and four-point loading. Based on the testing load-displacement relationship, ductility ratio, energy dissipation capacity of the beams were evaluated with comprehensive macro damage analysis on pultruded GFRP profile and GFRP wrapping. The GFRP wraps were established to have a major contribution to the composite beam ductility (90-125%) and strength (40-75%) in all ranges of beam behavior (shear-dominated or dominated by the coupling of shear and flexure). The composite beams with wraps were showns to reach ductilities and strength values of their counterparts with much greater beam depth.

Key Words
pultruded GFRP; GFRP wrapping; composite; hybrid beam; reinforced concrete

Yasin Onuralp Ozkilic and Emrah Madenci:Department of Civil Engineering, Necmettin Erbakan University, 42100, Konya, Turkey

Lokman Gemi:Meram Vocational School, Necmettin Erbakan University, 42100, Konya, Turkey

Ceyhun Aksoylu:Department of Civil Engineering, Konya Technical University, 42130, Konya, Turkey

Ilker Kalkan:Department of Civil Engineering, Kirikkale University, 71450 Kirikkale, Turkey

Proper calculation of splitting tensile strength (STS) of concrete has been a crucial task, due to the wide use of concrete in the construction sector. Following many recent studies that have proposed various predictive models for this aim, this study suggests and tests the functionality of three hybrid models in predicting the STS from the characteristics of the mixture components including cement compressive strength, cement tensile strength, curing age, the maximum size of the crushed stone, stone powder content, sand fine modulus, water to binder ratio, and the ratio of sand. A multi-layer perceptron (MLP) neural network incorporates invasive weed optimization (IWO), cuttlefish optimization algorithm (CFOA), and electrostatic discharge algorithm (ESDA) which are among the newest optimization techniques. A dataset from the earlier literature is used for exploring and extrapolating the STS behavior. The results acquired from several accuracy criteria demonstrated a nice learning capability for all three hybrid models viz. IWO-MLP, CFOA-MLP, and ESDA-MLP. Also in the prediction phase, the prediction products were in a promising agreement (above 88%) with experimental results. However, a comparative look revealed the ESDA-MLP as the most accurate predictor. Considering mean absolute percentage error (MAPE) index, the error of ESDAMLP was 9.05%, while the corresponding value for IWO-MLP and CFOA-MLP was 9.17 and 13.97%, respectively. Since the combination of MLP and ESDA can be an effective tool for optimizing the concrete mixture toward a desirable STS, the last part of this study is dedicated to extracting a predictive formula from this model.

Key Words
geotechnical engineering; metaheuristic optimizers; neural network; slope stability; soft computing

Juan Hu:School of urban construction, Zhejiang Shuren University, Hangzhou 310015, Zhejiang, China

Fenghui Dong:College of Civil Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China

Yiqi Qiu:Poly Changda Engineering Co., Ltd., Guangzhou 510620, Guangdong, China

Lei Xi: CCCC First Highway Survey, Design and Research Institute Co., Ltd., Xi'an 710075, Shaanxi, China

Ali Majdi: Department of Building and Construction Technologies Engineering, Al- Mustaqbal University College, 51001 Babylon, Iraq

H. Elhosiny Ali:1)Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics,
Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia
2)Research Center for Advanced Materials Science (RCAMS), King Khalid University,
P.O. Box 9004, Abha 61413, Saudi Arabia
3)Physics Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt

The aim of this paper is to study the mechanical behaviors of the cold-formed thin-walled steel and reinforced concrete sandwich composite slab (CTS&RC-SCS) under vertical loads and to develop the calculation methods of its flexural bearing capacity and section stiffness. Two CTS&RC-SCS specimens were designed and manufactured to carry out the static loading test, and meanwhile, the numerical simulation analyses based on finite element method were implemented. The comparison between experimental results and numerical analysis results shows that the CTS&RC-SCS has good flexural capacity and ductility, and the accuracy and rationality of the numerical simulation analysis are verified. Further, the variable parameter analysis results indicate that neither increasing the concrete strength grade nor increasing the thickness of C-sections can significantly improve the flexural capacity of CTS&RC-SCS. With the increase of the ratio of longitudinal bars and the thickness of the composite slab, the flexural capacity of CTS&RC-SCS will be significantly increased. On the basis of experimental research and numerical analysis above, the calculation formula of the flexural capacity of CTS&RC-SCS was deduced according to the plastic section design theory, and section stiffness calculation formula was proposed according to the theory of transformed section. In terms of the ultimate flexural capacity and mid-span deflection, the calculated values based on the formulas and the experimental values are in good agreement.

Key Words
calculation method; composite slab; flexural bearing capacity; parameter analysis; section stiffness

Wentao Qiao:1)School of Civil Engineering, Shi Jiazhuang Tiedao University, Shi Jiazhuang, China
2)Key Laboratory of Roads and Railway Engineering Safety Control (Shijiazhuang Tiedao University),
Ministry of Education, Shijiazhuang, Hebei Province ,050043, China

Zhiyuan Huang:School of Civil Engineering, Shi Jiazhuang Tiedao University, Shi Jiazhuang, China

Xiaoshuo Yan:1)School of Civil Engineering, Shi Jiazhuang Tiedao University, Shi Jiazhuang, China
2)3HeBei Institute of Building Architectural Design Limited Company, Shi Jiazhuang, China

Dong Wang:RC Companies, Baton Rouge, United States of America

Lijun Meng:School of Civil Engineering, Shi Jiazhuang Tiedao University, Shi Jiazhuang, China

Hybrid Steel-Trussed Concrete Beam (HSTCB) is structural typology suitable for light industrialization. HSTCBs usually cover long span with small depths, which lead to significant amount of longitudinal rebars. The latter make beamcolumn joints more prone to damage due to earthquake-induced cyclic actions. This phenomenon can be avoided using frictionbased BCCs. Friction devices at Beam-to-Column Connections (BCCs) have become promising solutions to reduce the damage experienced by structural members during severe earthquakes. Few solutions have been developed for cast-in-place Reinforced Concrete (RC) and steel-concrete composite Moment Resisting Frames (MRFs), because of the difficulty of designing costeffective damage-proof connections. This paper proposes a friction-based BCC for RC MRFs made with HSTCBs. Firstly, the proposed connection is described, and its innovative characteristics are emphasized. Secondly, the design method of the connection is outlined. A detailed 3D FE model representative of a beam-column joint fitted with the proposed connection is developed. Several monotonic and cyclic analyses are performed, investigating different design moment values. Lastly, the numerical results are discussed, which demonstrate the efficiency of the proposed solution in preventing damage to RC members, and in ensuring satisfactory dissipative capacity. members, and in ensuring satisfactory dissipative capacity

Key Words
friction connection; hybrid steel-trussed concrete beam; low-damage design; PerfoBond Connectors; RC structures

Piero Colajanni and Salvatore Pagnotta:Department of Engineering, University of Palermo Edificio 8, Viale delle Scienze, 90128, Palermo, Italy

This paper presents a numerical study to develop a guideline for estimating the plastic strength of elliptical steel slit damper with reasonable accuracy. The strut width increases from middle to end in elliptical steel slit damper and it is observed from the past studies that variation of the width is not considered for calculating the plastic strength of the damper. It is also noticed that the existing formulas for predicting plastic strength of this kind of damper may not be accurate and further refinement is warranted. Study is then carried on elliptical steel slit damper made of mild steel and having different geometry to find out equivalency of it with oblong steel slit damper having similar plastic strength. A few three-dimensional finite element models of seismic moment connection system with steel slit damper are developed and validated against past experiments for carrying the present study considering both the material nonlinearity as well as geometric nonlinearity. The results of the parametric studies have been compared with energy quantities and presented graphically to better understand the effects of different parameters on the system. Based on the pattern of parametric study results, closed-form semi-empirical algebraic expression of damper plastic strength is developed for elliptical steel slit damper which shows very good agreement with finite element analysis as well as experiments. This developed expression can now be used for elliptical steel slit damper in replacement with any type of damper in the design of moment connection.

Key Words
equivalency; plastic strength; seismic moment connection; semi-empirical algebraic expression

Mohammad I. Hossain and Khan M. Amanat:Department of Civil Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh

With the span and arch rib size of concrete-filled steel tube (CFST) arch bridges increase, the hydration heat of pumped mass concrete inside large-size steel tube causes a significant temperature variation, leading to a risk of thermal stressinduced cracking during construction. In order to tackle this phenomenon, a hydration heat conduction model based on hydration degree was established through a nonlinear temperature analysis incorporating an exothermic hydration process to obtain the temperature field of large-size CFST. Subsequently, based on the evolution of elastic modulus based on hydration degree and early-age creep rectification, the finite element model (FEM) model and analytical study were respectively adopted to investigate the variation of the thermal stress of CFST during hydration heat release, and reasonable agreement between the results of two methods is found. Finally, a comparative study of the thermal stress with and without considering early-age creep was conducted.

Key Words
analytical study; concrete-filled steel tube; early-age creep; hydration heat; temperature; thermal stress

Jinbao Xie:Department of Bridge Engineering, Tongji University, Shanghai 200092, China

Jianyuan Sun and Zhizhou Bai:1)Department of Bridge Engineering, Tongji University, Shanghai 200092, China
2)College of Civil and Architectural Engineering, Xinjiang University, Urumqi 830046, China

Surmounting complexities in analyzing the mechanical parameters of concrete entails selecting an appropriate methodology. This study integrates a novel metaheuristic technique, namely satin bowerbird optimizer (SBO) with artificial neural network (ANN) for predicting uniaxial compressive strength (UCS) of concrete. For this purpose, the created hybrid is trained and tested using a relatively large dataset collected from the published literature. Three other new algorithms, namely Henry gas solubility optimization (HGSO), sunflower optimization (SFO), and vortex search algorithm (VSA) are also used as benchmarks. After attaining a proper population size for all algorithms, the Utilizing various accuracy indicators, it was shown that the proposed ANN-SBO not only can excellently analyze the UCS behavior, but also outperforms all three benchmark hybrids (i.e., ANN-HGSO, ANN-SFO, and ANN-VSA). In the prediction phase, the correlation indices of 0.87394, 0.87936, 0.95329, and 0.95663, as well as mean absolute percentage errors of 15.9719, 15.3845, 9.4970, and 8.0629%, calculated for the ANN-HGSO, ANN-SFO, ANN-VSA, and ANN-SBO, respectively, manifested the best prediction performance for the proposed model. Also, the ANN-VSA achieved reliable results as well. In short, the ANN-SBO can be used by engineers as an efficient non-destructive method for predicting the UCS of concrete.

Key Words
CFSTC column; Concrete; Compression capacity; Neural computing; Satin bowerbird optimizer

Dizi Wu:School of Architecture, Changsha University of Science and Technology, Changsha 410004, China

Shuhua LI:China Construction Second Engineering Buerau LTD

Hossein Moayedi and Binh Nguyen Le:nstitute of Research and Development, Duy Tan University, Da Nang, Vietnam
4School of Engineering & Technology, Duy Tan University, Da Nang, Vietnam

Mehmet Akif CIFCI:Department of Computer Engineering, Bandirma Onyedi Eylul University, Balikesir 10200, Turkey

In order to improve the seismic resilience of coupled wall structure, coupling beam with fuse has been developed to reduce the post-earthquake damage. However, the fuses often have a build-up I-shaped section and are relatively heavy to be replaced. Moreover, the fuse and the beam segments are usually connected by bolts and it is time-consuming to replace the damaged fuse. For reducing the repair time and cost, a novel quickly replaceable coupling beam with buckling-restrained energy dissipaters is developed. The fuse of the proposed coupling beam consists of two chord members and bar-typed energy dissipaters placed at the corners of the fuse. In this way, the weight of the energy dissipater can be greatly reduced. The energy dissipaters and the chords are connected with hinge and it is convenient to take down the damaged energy dissipater. The influence of ratio of the length of coupling beam to the length of fuse on the seismic performance of the structure is also studied. The seismic performance of the coupled wall system with the proposed coupling beam is compared with the system with reinforced concrete coupling beams. Results indicated that the weight and post-earthquake repair cost of the proposed fuse can be reduced compared with the typical I-shaped fuse. With the increase of the ratio of the beam length to the fuse length, the interstory drift of the structure is reduced while the residual fuse chord rotation is increased.

Key Words
coupled wall; coupling beam; energy dissipater; quickly replaceable; seismic performance

Yong Li, Haifeng Yu:1)School of Civil Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, China
2)Innovation Center of Disaster Prevention and Mitigation Technology for Geotechnical and Structural Systems of Hebei Province
(Preparation), Shijiazhuang 050018, China
3)Engineering Technology Research Center for Intelligent & Low-Carbon Assembled Building, Shijiazhuang 050018, China

Xiaoyong Liang, Jianjun Yu, Pengcheng Li and Qizhi Wang: School of Civil Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, China

Wei Wang:State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures, Shijiazhuang Tiedao University,
Shijiazhuang 050043, China

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