Abstract
The headed stud is a critical component in steel-UHPC composite structures, with its shear strength significantly
affecting overall structural performance. Therefore, accurately predicting the shear capacity of headed stud is of paramount
importance. This study examines the shear strength of headed studs embedded in ultra-high-performance concrete (UHPC) and
develops a predictive model using interpretable machine learning techniques. A dataset of 577 push-out tests was established and
employed the advanced unsupervised Isolation Forest method to eliminate outliers. Then, five machine learning models
including the Linear Regression (LR), Decision Tree (DT), Random Forest (RF), Gradient Boosting Decision Tree (GBDT), and
Extreme Gradient Boosting (XGBOOST) were trained to predict the shear strength of headed studs embedded in UHPC. The
XGBoost model achieved the highest accuracy, with R2 value of 0.97. It outperformed the other models, thereby ensuring the
reliability of shear strength predictions for headed studs. To address the interpretability challenges associated with machine
learning models, feature importance was analyzed using Partial Dependence Plots (PDP), Individual Conditional Expectation
(ICE), and Shapley Additive explanations (SHAP). The results indicate that the cross-sectional area of headed stud has the
greatest influence on the shear performance, followed by the characteristics of UHPC and the tensile strength of headed studs.
Finally, utilizing the XGBOOST model for parameterized study of input features, a new equation for predicting the shear
strength of headed studs in steel-UHPC composite structures was established, combined with curve fitting methods. This
equation not only enhances the accurate prediction of shear performance but also provides insights into the machine learning models.
Address
Yuqing Hu: 1)Prefabricated Building Research Institute of Anhui Province, Anhui Jianzhu University, Hefei, 230601, China 2)State Key Laboratory of Safety, Durability and Healthy Operation of Long Span Bridges, Southeast University, Nanjing, 210096, China
Jiaxing Huang: Prefabricated Building Research Institute of Anhui Province, Anhui Jianzhu University, Hefei, 230601, China
Feng Zhang:College of civil engineering, Hunan University, Changsha, 410080, China
Zhe Wang: Prefabricated Building Research Institute of Anhui Province, Anhui Jianzhu University, Hefei, 230601, China
Ning Zhang :Prefabricated Building Research Institute of Anhui Province, Anhui Jianzhu University, Hefei, 230601, China
Jingquan Wang: State Key Laboratory of Safety, Durability and Healthy Operation of Long Span Bridges, Southeast University, Nanjing, 210096, China
Abstract
The concrete-filled steel hollow sections have been widely used as columns due to their superior structural
performance. The use of concrete in-fill produces higher compressive strength and reduces the buckling of steel hollow sections.
Nonetheless, recent studies have primarily concentrated on three types of concrete infill: normal concrete, high-strength
concrete, and lightweight aggregate concrete. Lightweight concrete could serve as an alternative to normal concrete, aiming to
reduce the dead weight of the concrete infill, such as Modified foamed concrete. Modified foamed concrete, which utilizes
minimal water and is considered more sustainable, has garnered significant attention as a potential structural material. However,
there has been little discussion on CFHS with modified fibrous foamed concrete. Therefore, this study aims to determine the
strength of fibrous-modified foam concrete-filled hollow sections. The foamed concrete infill is modified by adding Rice Hush
Ash (RHA) as a sand replacement and using steel and polypropylene fibres to improve its mechanical properties. Experimental
work is carried out to evaluate the structural performance of short columns made of modified fibrous foamed concrete-filled
hollow section (CFHS). The columns are tested under axial compression load to obtain their ultimate strength. The experiment
demonstrates that CFHS with fibrous foamed concrete achieves its theoretical value. The results indicate that incorporating
additional fibers increased the ultimate strength capacity by 10% to 13% compared to modified foamed concrete without fibers.
This confirms that the addition of fibers significantly enhances the ultimate strength capacity of CFHS. Moreover, quantitative
numerical analysis was conducted using ANSYS finite element software. The FEM analysis results closely align with the
experimental findings, particularly in terms of load-deflection behaviour and failure modes. Based on this analysis, an empirical
model for predicting the columns' ultimate strength was developed, showing strong agreement with the experimental data.
Address
S. A. A. Khairuddin: Mangkubumi Sdn Bhd, No. 23, Jalan Sungai Jeluh 32/191, Nouvelle Kemuning Industrial Park, 40460 Shah Alam, Selangor, Malaysia
N. Abd Rahman: Faculty of Civil Engineering and Built Environment, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Parit Raja, Johor, Malaysia
Z. Mohd Jaini: Faculty of Civil Engineering and Built Environment, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Parit Raja, Johor, Malaysia
A. Elamin: School of Engineering, Faculty of Engineering and Science, University of Greenwich, ME4 4TB, Chatham, United Kingdom
Abstract
Diagonal reinforcement placement in reinforced concrete (RC) coupling beams of tunnel form buildings is
impractical due to relatively small dimensions of such beams. Previous studies show that these elements acting as structural
fuses have minor contributions to overall seismic energy dissipation. In this study, we propose a novel perforated steel coupling
beam in lieu of the conventional RC coupling beam. We presented the relationships for determining the shear capacity of such
beams, and then investigated their validity numerically by using ABAQUS. The nonlinear seismic responses of the proposed
beam and conventional beam were compared and contrasted. The demand and capacity factors considering the influence of the
parameters such as ductility, over-strength, site seismic hazard and performance levels were also evaluated. The results indicate
that although steel-coupling beam reduces the global stiffness as compared to the RC coupling beam, it will not reduce the
building' s overall performance under the design earthquake. In fact, use of such beams increases the ductility and the response
modification factor. Their other advantages are easy to implement and repair or replace after an earthquake.
Key Words
coupling beam; earthquake; finite-element-modeling; fragility analysis; reliability; seismic hazard; tunnel
form building
Address
Sayed Ali Hussaini: Department of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran
Seyed Bahram Beheshti Aval: Department of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran
Abstract
These days, poor electronic waste (E-waste) disposal is polluting the environment and posing health risks in
developing nations. Prior research neglected post-damage retrofit efficiency in favor of concentrating on the compressive
execution of concrete compressive members reinforced with glass fiber reinforced polymer (GFRP). The purpose of this study is
to evaluate the mechanical execution of partly broken and retrofitted electronic waste aggregate concrete (EWC) compressive
members that have been reinforced with GFRP helix, bars, and synthetic fibers. Twelve circular specimens measuring 1000 mm
in height and 250 mm in diameter were retrofitted quickly using carbon fiber-reinforced polymer (CFRP) sheets. Six specimens
had steel bars and helix (SSEWC compressive members) and six specimens had GFRP bars and helix (GSEWC compressive
members) for main and transverse reinforcement. CFRP sheets applied for retrofit after load application caused a compressive
load-carrying capacity loss of up to 30% in the post-ultimate loading stage. Compressive load-carrying capacity, load-deflection
curves, compressive deflection, strength index, stiffness index, ductility index, and crack patterns were assessed pre-and postretrofit for the effects of monotonic axial and eccentric loading, CFRP casing, spiral vertical spacing, synthetic fibers, E-waste
concrete, and reinforcement Kind. Comparing the reconstructed SSEWC and GSEWC compressive members to their original
counterparts, the results showed improved mechanical execution.
Key Words
complex networks; mathematical simulation; mechanical behavior; nanotechnology
Address
Ali Raza: Department of Civil Engineering, University of Engineering and Technology Taxila, 47050, Pakistan
Mohd Ahmed: 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
Muhammad Awais: Department of Business Administration, Institute of Southern Punjab Multan, 66,000, Pakistan
Abstract
In recent years, steel reinforced concrete columns with encased steel ratios higher than 15% (HSR-SRC) have been
utilized in many high-rise buildings as the key bearing components at the bottom floors. This paper investigated the hysteretic
behaviour of the HSR-SRC columns. HSR-SRC columns with encased steel ratios above 15% exhibited excellent seismic
performance and behave more like the short compact steel columns rather than the SRC columns with normal encased steel
ratios. Although subjected to a high axial load ratio, HSR-SRC columns showed very mild degeneration of stiffness and
resistance in the post-peak load range, granting the columns good energy dissipation capacity and high ductility. The moment
resistance and total energy dissipation of the HSR-SRC columns were by and large directly proportional to the degree of the
extensiveness of the encased steel section, so the flexural and hysteretic performance of the HSR-SRC columns can benefit from
high shape distribution coefficient of the encased steel section. A finite-element modelling technique was developed allowing for
the four levels of confinement on the concrete provided by the hoops and encased steel section. The modelling technique was
able to accurately predict the hysteretic behaviour of the HSR-SRC columns. A new method was proposed to calculate the
resistance of HSR-SRC columns based on the static theorem of the limit analysis and three possible stress distributions. The
proposed method was validated against the collected experiment results and, with an average error of less than 5.8%, showed a
much better accuracy than the Eurocode 4 provision.
Key Words
design method; finite-element modelling; high encased steel ratio; hysteretic behaviour; shape of encased
steel section; SRC column
Address
Shen Yan: College of Civil Engineering, Tongji University, No.1239, Siping Road, Shanghai, China
Fuping Wen: College of Civil Engineering, Tongji University, No.1239, Siping Road, Shanghai, China
Xianzhong Zhao: College of Civil Engineering, Tongji University, No.1239, Siping Road, Shanghai, China
Yiyi Chen: College of Civil Engineering, Tongji University, No.1239, Siping Road, Shanghai, China
Abstract
Internal replacement pipe (IRP) is a novel trenchless repair technology for rehabilitating legacy gas and oil
pipelines. The current knowledge of the behaviour of IRP systems under repetitive traffic loading is limited due to insufficient
research work. This study aimed to examine how the bonding level between the host pipe and IRP affects the flexural fatigue
performance of IRP used for repairing legacy gas pipelines with circumferential discontinuities. The investigation was
conducted using numerical four-point bending simulations under both pressurised and non-pressurised conditions. The influence
of the thickness and material properties of IRP and the magnitude of traffic loads are also explored. The results of the analyses
showed that the minimum fatigue life of all pressurised systems with any bonding level is primarily controlled by the tensile
failure of the bottom outer surface of IRP. Based on a loading configuration of 762-1016-762 mm (30-40-30 in), it has been
determined that unbonding 311.2 mm (12.3 in) diameter IRP from the host pipe to a length at least equal to the diameter of the
IRP from the discontinuity edge provides the longest service life for non-pressurised repair systems. Similarly, for all pressurised
systems, the longest fatigue life can be achieved by unbonding them to a length of at least twice the diameter of the IRP from the
discontinuity edge.
