Abstract
The examination of crack growth's energy consumption in concrete structures has been of primary importance since
the origin of fracture mechanics. A quasi-brittle material like concrete heavily depends on the available fracture energy for
reliable design of structures and for modeling the failure spill. Yet, the approaches to evaluate the initial fracture energy of
concrete (IFEC) remain unsatisfactory because of complexity, time consuming costs and monetary budget constraints of
orthodox laboratory experiments. In this regard, this research suggested two predictive models: one is AdaGrad gated recurrent
unit (AdaG-GRU) and other is adaptive response surface method with KNN (ARSM-KNN). Chi-square automatic interaction
detection-decision tree (CHAID-DT) and automatic linear regression with boosting overfitting criteria (ALR-OPC) were also
included in the ensemble of the models, along with the stacking approach. Data from three-point load tests for single-edge
notched beams (SENB) conducted in the laboratory were used to train and validate these models. With the introduction of the
new empirical model using ALR-OPC, different scenarios of concrete strength were incorporated. The training was conducted
on a dataset which consisted of five features of concrete and one dependent variable as compressive strength, aged at 28 days,
and indexed by 500 datapoints, divided in 85 percent training and 15 percent testing set. These features included maximum size
of coarse aggregate and the ratio of water to cement. Between the offered metrics, multitask sensitivity analysis and importance
ranking identified the most crucial features of the IFEC as compressive strength and water-to-cement ratio. These results proved
the strongest correlation between the predicted and observed values using stacking-ensemble and AdaG-GRU models, which
obtained the highest accuracy at R2 = 0.98 and 0.95, respectively. Empirical laboratory tests and advanced machine learning
based models also agreed that the optimum water-to-cement ratio of 0.2 to 0.4 resulted in the maximum IFEC. In addition, the
increase of IFEC values with time was observed as maximum aggregate size and specimen age were increased from 1 mm to 35
mm and 3 to 180 days, respectively.
Key Words
concrete; hybrid-optimized machine learning; initial fracture energy of concrete; stacking-ensemble
Address
Manish Kewalramani:Department of Civil Engineering, College of Engineering, Abu Dhabi University, Abu Dhabi, UAE
Hanan Samadi:IRO, Civil Engineering Department, University of Halabja, Halabja, 46018, Iraq
Arsalan Mahmoodzadeh:IRO, Civil Engineering Department, University of Halabja, Halabja, 46018, Iraq
Nejib Ghazouani:Mining Research Center, Northern Border university, Arar 73222, Arar, Saudi Arabia
Abdulaziz Alghamdi:Department of Civil Engineering, University of Tabuk, Tabuk, Saudi Arabia
Ibrahim Albaijan:Mechanical Engineering Department, College of Engineering at Al-Kharj, Prince Sattam Bin Abdulaziz University, Al Kharj 16273, Saudi Arabia
Mohd Ahmed:Department of Civil Engineering, College of Engineering, King Khalid University, PO Box 394, Abha 61411 Kingdom of Saudi Arabia
Abstract
This study investigates the mechanical behavior of a multidirectional finned circular hollow steel damper
(MFCHSD) under cyclic loading by using numerical and analytical approaches. We propose to vary the surrounding an even
number of scraped curved fins, i.e., four, six, and eight pieces, to improve the performance of the slender circular hollow steel
damper (CHSD). The analytical approach implemented the classic analysis of shear stress distribution of thin walls, whereas the
numerical approach adopted the finite element method with continuum shell element. Important characteristics, such as shear
yield stress distribution, shear coefficient, shear yield strength, elastic stiffness, post-yield stiffness, and maximum strength, were
examined. These parameters are used to predict the maximum-to-yield strength ratio and the post-yield-to-elastic stiffness ratio,
which the important for the design of MFCSHD. Results suggest that the presence of additional fins increases CHSD
performance in the form of shear yield strength, maximum strength, and post-yield stability. In addition, the shear yield stress
distribution of the CHSD web was achieved, exhibiting good agreement between the analytical and the numerical approaches.
Finally, the shear yield strength of MFCSHD could be quantified using a novel formulation in accordance with the shear stress
distribution analysis.
Address
Ali Awaludin:Department of Civil and Envinromental Engineering, Universitas Gadjah Mada, Grafika Street 2,
Sleman, Special Region of Yogyakarta, Republic of Indonesia
Andika M. Emilidardi:Department of Civil and Envinromental Engineering, Universitas Gadjah Mada, Grafika Street 2,
Sleman, Special Region of Yogyakarta, Republic of Indonesia
Angga F. Setiawan:Department of Civil and Envinromental Engineering, Universitas Gadjah Mada, Grafika Street 2,
Sleman, Special Region of Yogyakarta, Republic of Indonesia
Iman Satyarno:Department of Civil and Envinromental Engineering, Universitas Gadjah Mada, Grafika Street 2,
Sleman, Special Region of Yogyakarta, Republic of Indonesia
Abstract
This paper proposes a novel prefabricated semi-rigid composite joint with the column and minor-axis beams
connected by channel steel components, which has no weakening effect on the column web and is easy to install with high
strength bolts. In this study, the mechanical behavior of the novel prefabricated semi-rigid composite joint under static and cyclic
loading are investigated by using ABAQUS. The FE modelling method is firstly verified to be correct. Then, to investigate the
mutual influence between major axis and minor axis under static and cyclic loading, the prefabricated composite joint is loaded
under different loading programs in this study. The results indicate that the novel prefabricated semi-rigid composite joint
proposed in this study has excellent static performance in terms of initial stiffness and load bearing capacity, as well as
satisfactory seismic performance in terms of energy dissipation ability and ductility. Furthermore, the initial stiffness, load
bearing capacity, deformability and energy dissipation ability of this proposed novel prefabricated semi-rigid composite joint is
greatly improved compared with that of the corresponding prefabricated semi-rigid steel joint. Thus, the connection method of
this novel prefabricated semi-rigid composite joint is proved to be reliable, efficient and easy to install on site, and this
composite joint shows good mechanical behavior meanwhile. Moreover, the influence of the interaction between the major and
minor axes of this novel prefabricated semi-rigid composite joint on the mechanical behaviors, especially for the initial stiffness
and ductility, should be considered.
Key Words
channel steel component; finite element analysis; prefabricated semi-rigid composite joints; seismic
performance; static performance
Address
Yong Cai:School of Civil Engineering, Central South University, Changsha 410075, China
Chang Liu:School of Civil Engineering, Central South University, Changsha 410075, China
Xiaoyong Lv:School of Civil Engineering, Central South University of Forestry and Technology, Changsha 410004, China
Jin Xie:School of Civil Engineering, Hunan City University, Yiyang 413000, China
Xueyi Zou:Infrastructure Department, Xiangtan University, Xiangtan 411105, China
Abstract
In this paper, we present an adapted Cross-Entropy Method (CEM) for the cost optimization of steel moment
frames, aimed at significantly reducing computational effort without compromising solution quality. Traditional CEM, while
effective, requires extensive structural analyses to identify elite solutions, leading to high computational costs. Our proposed
adaptation introduces a pre-screening phase where particles are initially sorted based on their estimated structural weight, a
proxy for cost-effectiveness. Only the most promising particles undergo full structural analysis, and those meeting structural
constraints are selected as elite particles. If the number of elite particles falls short of the required elite set in some iterations, the
method reverts to the traditional CEM approach for marking elites. This strategy not only reduces the number of structural
analyses required but also accelerates the convergence to optimal or near-optimal designs. Comparative studies demonstrate that
our adapted method achieves significant computational savings while maintaining, and in some cases improving, the quality of
the solutions. The proposed methodology offers a robust and efficient tool for structural engineers and designers seeking to
optimize steel moment frames under cost constraints.
Key Words
computational efficiency; cost optimization; cross-entropy method; pre-screening; steel moment frames
Address
Arash Naderi:Civil Engineering Department, University of Sistan and Baluchestan, Zahedan, Iran
Ali Mahallati Rayeni:Civil Engineering Department, University of Sistan and Baluchestan, Zahedan, Iran
Hamed Ghohani Arab:Civil Engineering Department, University of Sistan and Baluchestan, Zahedan, Iran
Abstract
Whilst recycled aggregate concrete (RAC) is increasingly being used in construction of slabs, there is still limited
data on the service performance of such structural elements. This article investigates the long-term behaviour of composite steel
concrete slabs cast with recycled aggregate concrete (RAC). The study addresses a gap in understanding the effect of RAC in
composite slabs subjected to sustained loads and human-induced vibrations. Various tests were conducted, including material
testing of RAC, non-uniform shrinkage tests on small-scale slabs, and long-term tests on full-scale slabs. The experimental
programme involved twelve slabs with dimensions of 0.15 m thickness x 1.0 m width, and varying lengths of 2.0 m, 3.0 m, 4.0
m or 5.0 m. The slabs were subjected to static loading, vertical sustained loading for 90 days, and human-induced vibrations
tests considering normal walking, brisk walking, and jumping. The results demonstrated that all slabs met the serviceability
limits outlined in current guidelines (ISO 2631-1), thus confirming the suitability of RAC for composite slab construction. The
vibration tests results showed that the RAC composite slabs performed well in service conditions, with vibration accelerations
for longer spans (5.0 m) being 24.3%, 8.3%, and 17.5% higher than for shorter spans (2.0 m) during normal walking, brisk
walking, and jumping, respectively. Despite these increases, all slabs remained within the vibration limits of ISO 2631-1. The
study also proposes a novel and practical semi-empirical equation to predict time-dependent deformations and creep, which is
validated through both experimental data and finite element analysis (FEA). The results from a parametric FEA further revealed
that slab vibration frequencies decreased by up to 22.8% as the span increased from 6.0 m to 12.0 m, highlighting the influence
of span length on performance. The proposed semi-empirical equation predicts accurately the time-dependent deformations with
a strong agreement between experimental and predicted results (Prediction/Experiment = 1.0). This study presents new
experimental data on the structural and serviceability behaviour of composite slabs made with 100% recycled concrete aggregate
(RCA), which is currently scarce in the literature. By advancing understanding of RAC's behaviour under realistic loading
conditions, the research contributes to the wider adoption of RAC and circular economy practices in construction of slabs.
Key Words
composite slabs; metal deck; recycled aggregate concrete; serviceability; vibrations
Address
Fetih Kefyalew:School of Engineering and Technology, Walailak University, Nakhon Si Thammarat, Thailand
Thanongsak Imjai:School of Engineering and Technology, Walailak University, Nakhon Si Thammarat, Thailand
Radhika Sridhar:School of Engineering and Technology, Walailak University, Nakhon Si Thammarat, Thailand
Reyes Garcia:Built Environment & Sustainability Research Cluster, School of Engineering, The University of Warwick, Coventry, U.K.
Abstract
Steel moment resisting frames (MRF) are one of the most widely used lateral load resisting systems for low- and
medium-rise buildings. Depending on the existing design constraints and assumptions, different alternatives of this lateral load
resisting system can be designed. Since one of the vulnerabilities of this structural system is its resistance to fire, this paper
studies the effect of different design parameters on the fire resistance of designed alternatives. As steel MRFs may be designed
with different ductility values, the main design parameter has been selected to be the ductility of frame in terms of being
intermediate or special. In addition, the effect of the number of stories, the gravity load level, and the location of fire in the width
and height of the structure have been studied. For this purpose, six intermediate and special MRFs with 3, 7, and 12 stories have
been numerically modeled and analyzed under different levels of gravity load and fire scenarios. To compare the results, a
comprehensive concept called "failure ratio" that shows the ratio of scenarios leading to failure to the total number of analyses at
each fire temperature, is introduced and used. Based on the results, frames designed for regions with high seismic risk show an
acceptable performance during the fire. In such regions, the use of both types of Intermediate Moment Frames (IMFs) and
Special Moment Frames (SMFs) can be recommended. On the other hand, frames designed for low seismic risk, are vulnerable
to fire and hence, it is crucial to check the fire resistance of MRFs in regions with a low seismic risk where the designed
structures have lower reserve strength. In these regions, using IMF frames can be considered a competitive or even better option.
Key Words
design parameters; Finite Element method (FEM); fire resistance; Gravity Load Ratio (GLR); Moment
Resisting Frame (MRF)
Address
Seyed Masood Miryousefi Aval:Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
Kazem Shakeri:Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
Vahid Akrami:Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
open access
