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Abstract
The reinforcement technology for rib-to-deck weld cracks in orthotropic steel deck should be both efficient and lightweight, particularly for multi-crack reinforcement within a single compartment, to avoid adding excessive weight that could affect the structural stress. In this paper, a lightweight reinforcement technology using ribbed angle steel was proposed. By conducting tests and numerical simulations, the reinforcement effect of ribbed angle steel for rib-to-deck weld cracks was analyzed, with a focus on the influence of stiffener thickness, spacing, and arrangement on the reinforcement effect. Reasonable parameters were then suggested. The effectiveness of the proposed technology and parameters was demonstrated through a real bridge simulation. The results show that ribbed angle steel, compared to angle steel, offers effective reinforcement while being lighter in weight. The failure behaviour of ribbed angle steel is consistent with that of plain angle steel, and the quality of adhesive layer construction should be strictly controlled during actual implementation. Increasing the thickness of the stiffeners can enhance the reinforcement effect, while increasing the spacing between stiffeners can reduce the reinforcement effect. When using ribbed angle steel with 4 mm thick angle steel, 6 mm thick stiffeners, and 20 mm stiffener spacing to reinforce cracks, the reinforcement effect is superior to that of 10 mm plain angle steel.

Key Words
crack reinforcement technology; orthotropic steel deck; parameter analysis; rib-to-deck weld crack; ribbed angle steel

Address
Yuqiang Gao, Zhongqiu Fu, Xuekun Cao and Bohai Ji:College of Civil and Transportation Engineering, Hohai University, No. 1 Xikang Road, Nanjing, China

Abstract
Enriched meshfree methods have been effectively used to predict the stress intensity factors (SIFs) and crack trajectories for homogeneous structures, but their applications to heterogenous materials were rarely reported. In this context, an enriched Petrov-Galerkin natural element method (PG-NEM) is introduced to simulate and examine the crack growth in 2-D heterogeneous functionally graded (FG) porous plates. The global displacement is approximated using Laplace interpolation (L/I) functions and enriched by introducing the crack-tip singular displacement and stress fields. The mixed-mode SIFs of FG plates characterized by the spatially varying elastic modulus are computed by the modified interaction integral method, and the crack trajectories are predicted by the maximum principal stress (MPS) criterion and the equivalent mode-I SIF. The advantage of proposed method is verified by comparing with the unriched PG-NEM and ANSYS. It is found that the prediction accuracy in crack trajectory is remarkably improved such that the crack trajectory of present method coincides well with one of ANSYS. Moreover, the present enriched method successfully simulates the crack trajectories of FG plates with the porosity as well as the spatially varying elastic modulus, and it is found that the crack growth characteristics are remarkably influenced by these parameters.

Key Words
2-D enriched PG-NEM; crack growth length; crack propagation trajectory; crack propagation; exponentially varying elastic modulus; functionally graded porous plates; porosity distribution

Address
J.R. Cho: Department of Naval Architecture and Ocean Engineering, Hongik University, Sejong 30016, Korea

Abstract
The proposed model introduces a novel approach to predicting stiffness and Poisson's ratio degradation in metal ceramic sandwich plates, specifically under hygro-thermo-mechanical loadings. Unlike previous models such as the Equivalent Constraint Model (ECM), this model incorporates an inter-laminar adhesive layer to transmit normal and shear stresses between the ceramic and metallic layers, significantly enhancing its accuracy in environmental stress simulation. By extending the shear lag model to include temperature and humidity effects, this model provides a more precise prediction of mechanical response under extreme operational conditions. Validation against experimental data further establishes the model's reliability, showing a substantial improvement in predictive capability. The Analysis reveals that both stiffness and Poisson's ratio degrade progressively with increasing crack density, temperature, and concentration, with the extent of degradation varying across metal content. Validated against experimental data, this model advances scientific understanding of metal-ceramic composite performance and provides a practical, accurate tool for designing resilient composites in demanding sectors such as aerospace and automotive, where environmental resilience is critical.

Key Words
hygro-thermo-mechanical; metal ceramic; poisson's ratio; shear-lag; stiffness; transverse cracking

Address
Mohamed Khodjet-Kesba:Aeronautical Sciences Laboratory, Institute of Aeronautics, and Space Studies, University of Blida 1, BP 270 Blida 09000, Algeria Zineb Mouloudj:Aeronautical Sciences Laboratory, Institute of Aeronautics, and Space Studies, University of Blida 1, BP 270 Blida 09000, Algeria Billel Boukert:Aeronautical Sciences Laboratory, Institute of Aeronautics, and Space Studies, University of Blida 1, BP 270 Blida 09000, Algeria

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
The bending moment has an extreme value at the middle support in steel-composite beam structures, while the concrete plate is liable to crack owing to the large tensile stress. In this study, based on a typical steel-concrete composite beam bridge, fatigue tests were carried out on two double-layer steel-composite beams. The results demonstrated that a significant nonlinear stage appeared before the failure of the shear nail and confirmed that the stiffness decline caused by slip can be ignored under the fatigue load, and the composite beam can be regarded as a complete shear connection. As the fatigue loading cycles increased, the stiffness of the steel-composite beam exhibited a nonlinear downward trend, with the declining speed increased rapidly at approximately 80% of the fatigue life. It can be stated that the slip growth theory of CEB-FIP MC90 can be adopted to predict the growth of crack width of steel-composite beam under static load test, which usually suffers from large prediction error under fatigue test owing to the strong constraints of the steel flange and welded nails. The conclusions of the study provide a reference for understanding the crack extension mode in the negative bending moment region of the steel composite beam under fatigue load and effectively controlling the crack width, which ultimately achieves the purpose of optimizing the performance of bridges and prolonging the service life of bridges.

Key Words
crack propagation; fatigue test; negative bending moment region; steel-composite beam; stiffness of cross section

Address
Kuan Li: School of Infrastructure Engineering, Dalian University of Technology, Dalian, 116024, China Yuanxun Zheng: School of Water Conservancy and Transportation, Zhengzhou University, Zhengzhou, Henan, 450001, China Pan Guo: School of Water Conservancy and Transportation, Zhengzhou University, Zhengzhou, Henan, 450001, China Pu Gao: Technology Center, China Construction Sixth Engineering Division Corp, Ltd., Tianjin, 300451, China Chao Wen: China Railway Engineering of Zhengzhou Seven Innings Group Co. Ltd., Zhengzhou, Henan, 450052, China

Abstract
Cracking of concrete slab in the negative moment area of steel-concrete composite continuous beam bridge is a fundamental issue affecting structural durability. The concrete slab cracks and the service crack width are determined according to factors associated with design, construction and operation conditions. In order to consider uncertainties involved in these factors, this paper conducted a probabilistic analysis on the concrete cracking in the negative moment area of steel-concrete composite continuous beams. A comprehensive risk probability assessment method for concrete cracking in negative moment area is proposed. In the probabilistic analysis, risk sources affecting the stress and maximum crack width in concrete slab are identified and quantified. The service crack width prediction model was proposed based finite element analysis, and the probability of cracking and service crack width exceeds the limit is calculated. A time-dependent probabilistic analysis is conducted for in-service composite bridge deck through modify the reinforcement stress and non-uniform coefficient considering the strain increment caused by concrete creep in tension and shrinkage. Based on the sensitivity analysis, cracking control recommendations are taken from the perspectives of constructability and material properties, and results revealed that the proposed control recommendations can effectively reduce the risk of concrete cracking in the negative moment area.

Key Words
concrete cracking; cracking control measures; negative moment area; risk probability; steel concrete composite continuous beam

Address
Huibing Xie:1)School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China 2)Key Laboratory of Safety and Risk Management on Transport Infrastructures, Ministry of Transport, Beijing 100044, China Bing Han:School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China Yue Sun:School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China Siyi Jia:School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China Wutong Yan:School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China

Abstract
In this study, seven steel and concrete composite beams (SCCBs) connected by T-shaped perfobond rib (PBL) shear connectors were tested to evaluate cracking performance in the hogging moment area. The selected parameters included the type of shear connectors, T-shaped PBL flange widths, and reinforcement ratios. The impact of these parameters on the crack distribution and load-crack width relationship was emphasized in this study. Finally, a modified method was developed that accounts for the T-shaped PBLs to estimate the average crack spacing and maximum crack width in the hogging moment regions of the composite beams. It was found that the flange enhances the cracking performance of the T-shaped PBL connectors. Compared with the composite beam with a flange width of 70 mm, the average crack spacing of 100 mm- and 130 mm-width decreased by 22% and 24%. The reinforcement ratio was a crucial factor affecting the cracking performance of the composite beam. The modified equations provided accurate predictions for the maximum crack width and mean crack spacing, with average calculated-to-test ratios of 0.92 and 1.00, respectively, and standard deviations of 0.11 and 0.09. This research could improve understanding of the cracking performance of SCCBs connected with T-shaped PBLs and provides guidance for crack control design.

Key Words
crack spacing; crack width; negative moment zone; steel-concrete composite beam; T-shaped PBL

Address
Wenfeng Huang: Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, China Yulin Zhan:1)Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, China 2)Institute of Civil Engineering Materials, Southwest Jiaotong University, Chengdu 610031, China Wenting Lyu:Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, China Hengjia Zhang:Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, China Haijun Jiang:Qingdao Municipal Engineering Design and Research Institute Ltd, Qingdao, 266000, China Junhu Shao:1)Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, China 2)School of Architecture and Civil Engineering, Chengdu University, Chengdu 610106, China

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