Conventional mode superposition methods for seismic analysis of underwater structures are based on modal orthogonality. However, they introduce errors when dealing with hydrodynamic problems because the hydrodynamic term does not actually satisfy this property. Additionally, previous studies for hydrodynamic responses often assumed structures to be fixed on a rigid base; however, the embedded portion of piles cannot provide sufficient rigidity for the submerged portion as the rigid base does. In this study, we propose an improved method that addresses the non-orthogonality of the hydrodynamic term by incorporating the hydrodynamic force contributions from other modes. Furthermore, the method accounts for base flexibility by modeling the embedded portion of a pile as an equivalent spring matrix. Comparisons with the conventional method indicate that the hydrodynamic effects from other modes are significant under flexible base conditions or when there is pile-head mass. Moreover, parametric analyses of pile seismic responses under near-fault and far-field earthquakes reveal that base flexibility and pile-head mass significantly influence the hydrodynamic forces and associated pile response envelopes, depending on the proximity between the system's resonance frequency and the predominant frequencies of the input motions.

The construction of steel-structure bridges is faster and less damaging to the environment than that of concrete bridges. However, the traditional scaffolding method often used to construct steel bridges fail to fully exploit these advantages. The incremental launching method (ILM) minimizes traffic disruption and working space during construction; therefore, this method is ideal for inaccessible sites or where construction interference must be minimized. Despite its benefits, ILM is primarily used for constructing concrete bridges; it has rarely been applied for constructing steel-structure bridges. This article explores the advantages and applicability of the ILM for constructing steel-structure cable-stayed bridges by considering the new Dazhu Bridge in Taoyuan, Taiwan, as a case study. This bridge spans a 110-m highway, and its design requirements prohibit the creation of piers on the highway or the disruption of highway traffic. We compared the performance of the ILM and scaffolding method for single-span cable-stayed bridges with a focus on structural models, usage specifications, and construction methods. The incremental launching of steel structures can considerably reduce traffic interference and construction time while improving construction quality and safety. This method combines techniques for concrete bridge superstructure construction, such as the precast segment method, ILM, and ASM. © 2025 The Chinese Institute of Engineers.

This paper presents reduced model tests on geosynthetic-reinforced soil (GRS) embankment and foundation systems subjected to reverse fault movements. Three types of reinforced foundations - soil foundations reinforced with planar geotextiles, geosynthetic encased granular columns (GECs), and geocells - were examined to investigate the effectiveness and reinforcing mechanisms in mitigating reverse fault-induced ground deformation. Digital image analysis (DIA) techniques were adopted to evaluate the surface displacement profiles, maximum angular distortion (βmax), and shear strain contours at different magnitudes of reverse fault displacement. The maximum horizontal facing displacement (Δmax) of the overlying GRS embankment was also determined to evaluate the overall performance of the GRS embankment and foundation systems. Test results indicated that different reinforcing mechanisms and the development of fault-induced shear ruptures were observed for three types of reinforced foundations. The geocell foundation had the most optimal effects in minimizing the βmax at the ground surface, as well as the Δmax of the GRS embankment. Compared with the unreinforced foundation, a reduction of 39.1% in the Δmax value of the GRS embankment was observed at a fault movement to foundation thickness ratio (S/HF) of 37.5%. For all the reinforced embankment and foundation systems, the overlying GRS embankment remained stable, and only localized deformation on the wrapped-around facing was observed. The influence of overburden pressure applied by the GRS embankment on the performance of each reinforced foundation, as well as the design implications of the embankment and foundation systems, were discussed in the present study. © 2025 American Society of Civil Engineers.

Pei-Lin Lee serves as Clinical Associate Professor, School of Medicine, National Taiwan University; Consultant, Center of Sleep Disorder, National Taiwan University Hospital. Her current academic positions at international sleep societies include American Academy of Sleep Medicine Fellow and Co-Chair International Assembly; Asian Society of Sleep Medicine, Sleep Medicine Education Task Force committee member. Her current research focuses on the era of new technology and big data in sleep medicine; and intervention on sleep and metabolism in sleep disordered breathing.