Page(s): 154-165 Hung Nguyen Dinh, Thang Nguyen Tu, Tien Nguyen DVT Thuy, Ven Phan Lam, Linh Tran NgocAbstractStirrups are normally arranged from 45° to 90° to a beam axis to prevent shear crack and improving the shear carrying capacity of the normal reinforced concrete (RC) beams designed horizontally. However, in inclined RC elements, stirrups were arranged parallelly or vertically to the earth surface to be constructed easily. Under uncertain direction load such as earthquake, wind water pressure or collision loads and so on, the angle of stirrup could become larger than 90°. In that case, the contribution of the stirrups on shear carrying capacity can be minimized and the shear transferring mechanism can be changed. This paper presents experimental results on RC beams with the inclined angle of stirrups of 90°, 105°, 125° và 135°. The results showed that all tested beams were failed in shear compression mode. The angle of the critical shear crack in the RC beam with the inclined angle of stirrup greater than 90° was guided by the inclined stirrup. Therefore, the larger the inclined angle of the stirrup is, the smaller the angle of critical shear crack is and the smaller the shear carrying capacity of the beam is. The experimental result also showed that the inclined angle of stirrups should not be larger than 105°.
Page(s): 166-180 Che Le Van, Tan Dang Minh, Cay Bui XuanAbstractThe acute lack of parking spaces in Hanoi capital, combined with rising urban traffic pressure, makes predicting drivers’ parking location choices critically important. This study applies a Support Vector Machine (SVM) model to predict on-street parking location choice behavior in Hanoi. Input data were collected through questionnaire-based surveys administered directly to car drivers across different urban areas. The SVM model was evaluated using standard performance metrics. In addition, the study integrates model interpretation techniques, including SHapley Additive exPlanations (SHAP) and Partial Dependence Plots (PDP), to clarify the relative importance and directional effects of influencing factors. The results indicate that the SVM model achieves high classification and prediction performance. Parking location choice behavior is primarily influenced by pricing mechanisms, road hierarchy, sidewalk characteristics, and congestion risk, while demographic factors exhibit limited impact. The results of this study offer several valuable implications and provide a scientific basis for the planning, design, and operation of parking systems in Hanoi.
Page(s): 181-195 Duong Pham TuyenAbstractGround deformation induced by tunnelling in saturated soft ground is a critical issue affecting construction safety and the stability of adjacent structures. This study investigates ground deformation trends around tunnels using a Displacement-Controlled Model (DCM) within the framework of the Finite Element Method (FEM), under the assumption of small-strain behaviour. The tunnelling process is represented by prescribed displacements along the tunnel boundary, reflecting the mechanism of ground convergence towards the tunnel void during excavation. The model is validated against The Heathrow Express Trial Tunnel, in which the difference in maximum surface settlement is less than 5% compared with field monitoring data, demonstrating a good agreement in terms of deformation shape and trend. Based on the validated model, a systematic parametric study is conducted to examine the influences of tunnel diameter, burial depth, and volume loss ratio on ground deformation. The results indicate that the maximum settlement increases almost linearly with tunnel diameter, decreases significantly with increasing burial depth, and rises nonlinearly when the volume loss ratio exceeds approximately 1.5%. A case study of Ho Ch```i Minh City Metro Line No. 1 (Ben Thanh - Suoi Tien section) shows that the DCM approach can reasonably capture ground deformation trends under similar geological conditions. The findings provide a useful reference for trend assessment of ground deformation and surface settlement in urban tunnelling problems, without aiming to replace detailed design analyses.
Page(s): 196-208 My Cao Thi Xuan, Tan Van HongAbstractThe Theory of Planned Behavior (TPB) has been widely applied in behavioral research; however, studies on electric vehicles (EVs) have reported inconsistent findings regarding the relative influence of its antecedent constructs on behavioral intention. This study employs a two-stage meta-analytic structural equation modeling (TS-MASEM) approach to evaluate an extended TPB model incorporating Environmental Concern (EC) within the context of emerging economies. Data extracted from 31 empirical studies across 30 journal articles were coded to estimate effect sizes among five constructs based on ten correlations. The results reaffirm the validity of the constructs within the TPB model in explaining behavioral intention and reveal that EC exerts an indirect positive effect on intention through attitude, thereby highlighting the critical mediating role of attitude in EV adoption behavior. Overall, these findings strengthen the empirical foundation of the extended TPB and provide valuable evidence. Finally, policy implications are proposed to support sustainable mobility transitions in developing countries such as Vietnam.
Page(s): 209-223 Hieu Tran Van, Tuan Do Duc, Toan Nguyen DucAbstractFor imported mechanical equipment, including the CAT 3512B engine used on the China-manufactured D19E diesel locomotive, the documentation supplied by manufacturers is typically restricted to fundamental technical specifications. In contrast, reliability-related parameters established during the design and production stages, which are essential for operational performance and maintenance planning, are seldom made available. Consequently, it becomes necessary to evaluate the reliability of key locomotive subsystems, particularly the engine crankshaft bearing system. The crankshaft bearing system of a diesel engine is composed of journal bearings operating under hydrodynamic lubrication. From the standpoint of reliability engineering, this system may be modeled as a series configuration consisting of multiple components, in which failure of any individual element can lead to functional failure of the entire system. Accordingly, this study was performed in order to apply reliability theory to journal bearing interfaces in order to estimate the reliability of each individual joint and to assess the overall reliability of the crankshaft bearing system of the CAT 3512B engine installed on the D19E diesel locomotive before operational deployment.
