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CONTENTS
Volume 53, Number 2, October 25 2024
 

Abstract
These days, cement production is increasing due to the growing world population, leading to expanded use of concrete in buildings. Yet, the production of cement significantly increases carbon emissions, putting the future of sustainable development at risk. Geopolymers are under research for their potential to reduce the impact on concrete buildings. In order to tackle this issue, the literature has yet to utilize experiments or numerical modeling to thoroughly investigate the mechanical behavior of columns made of hybrid fiber-reinforced geopolymer concrete (HFRGC) and reinforced with basalt fiber reinforced polymer (BFRP) bars. This research aims to investigate and assess the mechanical performance of steel-reinforced HFRGC columns (SRHC) and BFRP-reinforced HFRGC columns (GRHC) in concentric and eccentric loading conditions through experimental testing and finite element analysis (FEA). HFRGC specimens were prepared using steel and polypropylene fibers. Twelve circular columns, six GRHC, and six SRHC specimens, were constructed with a diameter of 300 mm and a height of 1200 mm. The average axial strength (AS) of GRHC columns was found to be 92.13% of that of SRHC columns, according to the study. Under eccentric stress circumstances, both kinds of specimens showed comparable losses in AS; for example, GRHC specimens with 38 mm spiral spacing showed reductions of 39.01% and 43.12%. Good performance was shown by the suggested analytical relationships that were drawn from the experimental data. The AS of GRHC columns may be predicted using the newly established analytical and FEA models, which are well supported by this comparative analysis that takes into account the wrapping impact of lateral BFRP spirals and the axial participation of primary BFRP bars.

Key Words
BFRP spiral; concrete damaged plastic model; deformability; finite element analysis; geopolymer

Address
Ali Raza:Department of Civil Engineering, University of Engineering and Technology Taxila, 47050, Pakistan

Nejib Ghazouani:Civil Engineering Department, College of Engineering, Northern Border University, Arar 73222, Saudi Arabia

Mohamed Hechmi El Ouni:1)Department of Civil Engineering, College of Engineering, King Khalid University, PO Box 394, Abha 61411, Saudi Arabia
2)Center for Engineering and Technology Innovations, King Khalid University, Abha 61421, Saudi Arabia

Abstract
The bridge hanger is exposed to cyclic loads, such as wind and vehicle loads, which can induce fatigue failure, significantly reducing its operational lifespan. Additionally, the hanger is prone to corrosion throughout transportation, construction, and operation. Although corrosion fatigue curves are typically derived from individual steel wire experiments, the bridge hanger comprises multiple parallel steel wires. Consequently, a corrosion fatigue curve based on a single wire may not accurately portray the hanger'slongevity, and data solely at the component level may not encompass the overall system-level condition. To tackle this challenge, this paper introduces a series system-level reliability assessment framework based on dynamic Bayesian Networks, accounting for the interdependence between variables. Specifically, the framework encompasses a time-varying reliability model featuring three random parameters (corroded number, equivalent structural stress, and the total cycles number of wires) and leverages seven numerical simulation studies to investigate the impacts of these random parameters on system reliability.

Key Words
corrosion fatigue; dynamic bayesian network; parallel steel wire; S-N curve; series system; system-level assessment reliability

Address
Yang Ding:1)Key Laboratory of Transport Industry of Bridge Detection Reinforcement Technology, Chang'an University, Xi'an 710064, China
2)Department of Civil Engineering, Hangzhou City University, Hangzhou 310015, China
3)State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing 400074, China

Chao-Dong Guan:Department of Civil Engineering, Hangzhou City University, Hangzhou 310015, China

Jian Zhou:Department of Civil Engineering, Hangzhou City University, Hangzhou 310015, China

Tian-Yun Chu:Jiaxing Tiankun Construction Engineering Design Co., Ltd., Jiaxing 314000, China

Xue-Song Zhang:State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing 400074, China

Abstract
Identifying the location of earthquake-induced damage in buildings and mitigating its impact, especially in lowdamage systems such as rocking frames, is a significant challenge for structural engineers. Therefore, it is crucial to investigate the sensitivity and type of damage of buildings exposed to severe earthquakes to concentrate damage in predefined locations that can be repaired easily. This paper explores the seismic responses of a Self-Centering Rocking Steel Braced Frame (SCR-SBF) under far-field and near-field ground motions. This earthquake-resistant system includes components such as post-tensioning cables to provide frame self-centering, eliminate residual drift in the system, and replaceable fuses to concentrate the earthquakeinduced damage. While previous studies have examined far and near-field earthquakes, their comparative influence on the seismic behavior of structures with a rocking system remains unexplored. This paper presents a novel investigation into the sensitivity of SCR-SBF structures to far and near-field earthquakes. Considering the critical effects of shock and impulse loads on rocking systems, the study aims to assess the effects of near-field earthquakes and compare them to far-field earthquakes on these systems. For this purpose, different response parameters have been calculated under records of far- and near-field earthquakes at three specific ground acceleration levels by incremental nonlinear dynamic analysis. Additionally, the seismic behavior of the SCR-SBF and Steel-Braced Frame (SBF) are compared for near and far-field ground motions. The results show that SCR-SBF systems have better resilience and reduced local failures compared to SBF systems under far and near-field earthquakes, requiring tailored design strategies.

Key Words
fuses; low damage system; seismic force-resisting system; seismic performance; self-centering rocking steel braced frame

Address
Masoomeh Naraghi:Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran

S. Mohammad Mirhosseini:Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran

Hossein Rahami:School of Engineering Science, College of Engineering, University of Tehran, Tehran, Iran

Abdolreza S. Moghadam:International Institute of Earthquake Engineering and Seismology, Tehran, Iran

Abstract
Although the excellent characteristics of functionally graded materials (FGMs) cracks could be found due to manufacturing defects or extreme working conditions. The existence of these cracks may threaten the material or structural strength, reliability, and lifetime. Due to high cost and restrictions offered by practical operational features these cracked components couldn

Key Words
dynamic finite element; exponential gradation; functionally graded cracked beams; moving load; rotational; spring model; Timoshenko shear locking free; Winkler elastic foundation

Address
Alaa A. Abdelrahman:Mechanical Design & Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Mohamed Ashry:Mechanical Design & Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Amal E. Alshorbagy:Mechanical Design & Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Mohamed A. Eltaher:1)Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, Saudi Arabia
2)Department of Mechanical Design & Production, Faculty of Engineering, Zagazig University, Zagazig, Egypt

Waleed S. Abdalla:1)Mechanical Design & Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt
2)Mechatronics Department, Faculty of Engineering, Horus University, New Damietta, Egypt

Abstract
This study focused on the cyclic behavior of Triangular-plate Added Damping and Stiffness (TADAS) and the impact of axial force on its performance. First, the numerical model was verified, and the impact of damper dimensions on elastic and effective stiffness, ultimate strength, energy dissipation, and equivalent viscous damping ratio (EVDR) was studied. The numerical results were then used to propose approximate equations to estimate these findings. In the second section, the buckling load of TADAS was calculated analytically, and an approximate equation was presented to facilitate estimation. The effects of axial force on elastic stiffness, ductility, and ultimate strength were then investigated. This study found that decreasing the height, increasing the width, and increasing the middle width of TADAS improved its energy absorption, effective stiffness, and ultimate strength. The EVDR results improved with decreasing height, increasing width, and middle width. Approximate equations provided results that were close to numerical results, indicating that they are reliable for calculating seismic parameters. The damper's ultimate strength was most affected by the axial force. In the most affected model, an increase in axial force of 0.025 Pcr (Buckling load of the damper) reduced ultimate strength, ductility, and elastic stiffness by 26%, 22%, and 16%, respectively.

Key Words
axial load; ayielding damper; cyclic behavior; numerical analysis; TADAS damper

Address
Kambiz Cheraghi:Department of Civil Engineering, Faculty of Engineering, Razi University, Kermanshah, Iran

Mehrzad TahamouliRoudsari:Department of Civil Engineering, Faculty of Engineering, Razi University, Kermanshah, Iran

Abstract
In the present study, the third-order shear deformation theory (TSDT) is presented to investigate time-dependent thermo-elastic creep behavior and life assessment of rotating thick cylindrical shells with variable thickness made of 304L austenitic stainless steel (304L SS). The cylindrical shells are subjected to non-uniform internal pressure, distributed temperature field, and a centrifugal body force due to rotating speed. Norton's law is used to describe the material creep constitutive model. A system of differential equations in terms of displacement and boundary conditions is derived by employing the minimum total potential energy principle based on TSDT. Then, the resulting equations are solved as semi-analytically using the multilayered method (MLM), which leads to an accurate solution. Subsequently, an iterative procedure is also proposed to investigate the stresses and deformations at different creep times. Larson-Miller Parameter (LMP) and Robinson's linear life fraction damage rule are employed to estimate the creep damages and the remaining life of cylindrical shells. In this research, the creep model uses Norton's law, LMP, and Robinson's approach which is the most accurate and reasonable model. To the best of the researcher's knowledge, in the previous studies, there is no study carried out on third-order shear deformation theory for thermoelastic creep analysis and life assessment of thick cylinders with variable thickness. The results obtained from the multilayered approach are compared and validated with those determined from the finite element method (FEM) to confirm the accuracy of the suggested method based on TSDT and very good agreement is found. The results indicate that the present analysis is accurate and computationally efficient.

Key Words
304L austenitic stainless steel; creep; life assessment; rotating thick cylindrical shell; third-order shear deformation theory (TSDT); variable thickness

Address
Tahereh Taghizadeh and Mohammad Zamani Nejad:Department of Mechanical Engineering, Yasouj University, Yasouj, Iran

Abstract
Advancements in additive manufacturing technology, notably for its efficiency, accuracy, automation, and streamlined procedures, are increasingly relevant in civil engineering. This study evaluates the mechanical properties of 316L stainless steel bolted connections fabricated using Powder Bed Fusion (PBF) additive manufacturing. Eleven single-lap bolted connection specimens were tested under monotonic loading to assess the influence of various factors, including plate thickness, manufacturing direction, bolt end and edge distances, and bolt quantity, on the connections' anti-sliding and shear capacities. Material tests conducted prior to the connection tests revealed that PBF-manufactured stainless steel plates possess higher yield and ultimate strength, as well as greater elongation capacity, compared to traditional stainless steel plates. The connection tests indicated that the anti-sliding coefficient values range from 0.348 to 0.698, aligning with current standards for stainless steel bolted connections. Three distinct failure modes were identified: net section failure in the stainless-steel plate, bolt shear failure, and plate shear failure. It was determined that existing standards for anti-sliding capacity may not be entirely applicable to PBFmanufactured connections. Therefore, a modified model for the anti-sliding capacity of these connections is proposed. Additionally, a more accurate formula for calculating their shear capacity, which addresses the oversight of friction forces in current standards, is introduced.

Key Words
additive manufacturing; stainless steel bolted connections; anti-sliding coefficient; anti-sliding capacity; shear capacity

Address
Zhengyi Kong:1)Department of Civil Engineering, Anhui University of Technology, China
2)Institute for Sustainable Built Environment, Heriot-Watt University, United Kingdom

Ningning Hu:Department of Civil Engineering, Anhui University of Technology, China

Ya Jin:Department of Civil Engineering, Anhui University of Technology, China

Kun Xing:1)Department of Civil Engineering, Anhui University of Technology, China
2)Key Laboratory of Multidisciplinary Management and Control of Complex Systems of Anhui Higher Education Institute, Anhui University of Technology, China

Qinglin Tao:Department of Civil Engineering, Anhui University of Technology, China

George Vasdravellis:Institute for Sustainable Built Environment, Heriot-Watt University, United Kingdom

Duc Kien Thai:Dept. of Civil and Environmental Engineering, Sejong University, South Korea

Quang-Viet Vu:1)Laboratory for Computational Civil Engineering, Institute for Computational Science and Artificial Intelligence,
Van Lang University, Ho Chi Minh City, Vietnam
2)Faculty of Civil Engineering, School of Technology, Van Lang University, Ho Chi Minh City, Vietnam

Abstract
Conventional carbon mild steel is a type of steel known for its low carbon content and generally used in the construction industry. Its easily formable and weldable properties make this steel a widely preferred material for buildings, bridges and various construction projects. Other advantages of these steels are their low cost and good mechanical properties. However, high temperatures have an impact on the microstructure and mechanical characteristics of these materials. When high temperatures are present during a fire, steels show significant microstructural changes. Elevated temperatures often decrease the mechanical characteristics of steels. For this purpose, evaluating the post-fire behavior of conventional structural mild steel is an important issue in terms of safety. A combined experimental and parametric study was conducted to estimate fire damage to steel buildings, which is an important issue in the construction field. Tensile test coupons were cut from conventional structural S235JR mild steel sheets with thicknesses ranging from 6 mm to 12 mm. These samples were exposed to temperatures as high as 1200 °C. After heat treatment, the specimens were allowed to naturally cool to ambient temperature using air cooling before being tested. A tensile test was performed on these coupons to evaluate their mechanical properties after fire, such as their elastic modulus, yield strength, and ultimate tensile strength. The mechanical behavior of conventional S235JR structural steel changed significantly when the heating temperature reached 600°C. The thickness of the steel had a negligible effect on yield strength loss, with the highest measured loss being 50% for 8 mm thickness at 1200°C. The modulus of elasticity remained almost constant up to 800°C, but at 1200°C, the loss reached around 20% for thicker sections (10 mm and 12 mm) and up to 35% for thinner sections (6 mm and 8 mm). Overall, high temperatures led to significant deterioration in both yield and ultimate strength, with a general loss of load-bearing capacity above 600°C. A new equation was formulated from experimental results to predict changes in the mechanical properties of S235JR steels. This equation offers a precise evaluation of buildings made from conventional structural S235JR mild steel after fire exposure. Furthermore, the empirical equation is applicable to low-strength steels with yield strengths ranging from 235 MPa to 420 MPa.

Key Words
conventional structural mild steel; empirical equations; mechanical behavior; post-fire; S235JR

Address
Özer Zeybek:Department of Civil Engineering, Faculty of Engineering, Mugla Sitki Kocman University, Mugla 48000, Turkey

Veysel Polat:Department of Civil Engineering, Faculty of Engineering, Mugla Sitki Kocman University, Mugla 48000, Turkey

Yasin Onuralp Özkilic:1)Department of Civil Engineering, Faculty of Engineering, Necmettin Erbakan University, Konya 42000, Turkey
2)Department of Technical Sciences, Western Caspian University, Baku, 1001, Azerbaijan

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