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"Dynamic testing"
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Seismic Strengthening of R/C Buildings Retrofitted by New Window-Type System Using Non-Buckling Slit Dampers Examined via Pseudo-Dynamic Testing and Nonlinear Dynamic Analysis
In the present study, a window-type seismic control system (WSCS) using non-buckling slit dampers (NBSDs) was proposed and developed to address the disadvantages of conventional seismic control systems so that it can be effectively applied to existing reinforced concrete (RC) buildings. Materials testing was also conducted to examine the material performance and energy dissipation capacity of NBSD. A full-scale two-story test frame modeled from existing RC buildings with non-seismic details was subjected to pseudo-dynamic testing. As a result, the effect of NBSD-WSCS, when applied to existing RC frames, was examined and verified, especially as to its seismic retrofitting performance. In addition, based on material testing and pseudo-dynamic test results, a restoring force characteristics model was proposed to implement the nonlinear dynamic analysis of a test building retrofitted with NBSD-WSCS. Based on the proposed restoring force characteristics, nonlinear dynamic analysis was conducted, and the results were compared with those obtained by the pseudo-dynamic tests. Finally, in an attempt to commercialize this NBSD-based WSCS, nonlinear dynamic analysis was conducted on the entire RC building with non-seismic details retrofitted with NBSD-WSCS. The results showed that the RC frame (building) with no reinforcement applied underwent shear failure at seismic intensity of 200 cm/s2, a typical threshold applied in seismic design in Korea. In contrast, in the frame (building) retrofitted with NBSD-WSCS, only minor earthquake damage was expected, and even when the seismic intensity was set to 300 cm/s2, the maximum intensity that had been observed in Korea, only small or moderate seismic damage was expected. These results confirmed the effectiveness of the seismic retrofitting method using NBSD-WSCS developed in the present study.
Journal Article
Shear Capacity of Fiber-Reinforced Polymer Beams Without Stirrups: Comparative Modeling with FRP Modulus, Longitudinal Ratio, and Shear Span-to-Depth
This study develops data-driven models for predicting the shear capacity of reinforced concrete (RC) beams longitudinally reinforced with fiber-reinforced polymer (FRP) bars and lacking transverse reinforcement. Owing to the comparatively low elastic modulus and linear–elastic–brittle behavior of FRP bars, reliable shear prediction remains a design challenge. A curated database of 402 tests was compiled from the literature, spanning wide ranges of beam size (width b, effective depth d), concrete compressive strength (f′c ), FRP elastic modulus (Ef ), longitudinal reinforcement ratio (ρf ), and shear span-to-depth ratio (a /d ). Multiple multivariate regression formulations—both linear and nonlinear—were developed using combinations of these variables, including a mechanics-informed reinforcement index (ρf ·Ef ). Model predictions were benchmarked against 15 existing expressions drawn from design codes, standards, and prior studies. Across the full database, the proposed models demonstrated consistently stronger agreement with experimental results than the existing predictors, yielding higher correlation and lower prediction error. The resulting closed-form equations are transparent and straightforward to implement, offering improved accuracy for the preliminary design and assessment of FRP-RC beams without stirrups while highlighting the influential roles of Ef , ρf , and a /d within the observed parameter ranges.
Journal Article
Dynamic testing with graduated prompts training: Adolescents with executive function deficits
Introduction: Adolescents with executive function deficits have difficulties performing complex daily tasks. Process- oriented dynamic testing with graded prompts training offers valuable insights to improve adolescents' thinking and performance abilities in occupational therapy interventions. This study explores the effectiveness of graded prompts training in improving performance during the Rey-Osterrieth Complex Figure (ROCF) task. Method: This secondary analysis included data from 41 adolescents with executive function deficit profiles who had participated in the therapeutic occupational therapy intervention program 'Functional Individualized Therapy for Teenagers'. Dynamic pre- and post-test phases, focused on copying and immediate recall, were assessed using accuracy, placement, and organization strategy scores. Results: Results indicate significant improvements following graded prompts training in copying and memory accuracy (67% and 180%), placement (49% and 237%), and organization strategy (66% and 99%). Positive correlations were observed between improved copying accuracy and organization, memory accuracy and organization, and copying and memory organization (p <.001). Conclusion: Graded prompts training May improve the performance of adolescents with executive function deficits during complex tasks (e.g., ROCF). Future research should explore the training's long-term effects and applications in diverse clinical settings to validate further and expand these promising results. This training could become integral to therapeutic interventions for enhancing this population's daily functioning and overall well-being.
Journal Article
Structural Response of Post-Tensioned Slabs Reinforced with Forta-Ferro and Conventional Shear Reinforcement under Impact Load
Several researchers have studied how impact loads from impact hazards affect reinforced concrete (RC) slabs. There is relatively little research on impact loading effects on pre-stressed structures. The usage of fibers in structural elements intrigued researchers. In this paper, impact-loaded post-tensioned (PT) slabs with and without Forta-Ferro fibers were compared to post-tensioned slabs with plain concrete and conventional shear reinforcement. Forta-Ferro is a lightweight, low-cost fiber, and hence its effects on slab structural response under impact load deserve to be explored. Post-tensioned slabs’ impact resistance and energy absorption were tested using real-world situations of rapid and severe loads. Four identical 3.3 by 1.5 m concrete slabs were utilized in the experiment. The experiment involved dropping a 600 kg iron ball from 8 m onto each slab’s center of gravity. The slabs’ responses were investigated. The four slab configurations were tested for displacement, energy absorption, and cracking. Forta-Ferro fiber reinforcement is understudied, making this study significant. The study’s findings may help us comprehend fiber-reinforced concrete PT slabs’ impact resistance and structural performance. Engineers and designers of impact-prone buildings like slabs and bridges will benefit from the findings. The study also suggests adding Forta-Ferro fibers to post-tensioned slabs to improve durability and resilience against unanticipated impact hazards.
Journal Article
Damage Identification of Piles Based on Vibration Characteristics
A method of damage identification of piles was established by using vibration characteristics. The approach focused on the application of the element strain energy and sensitive modals. A damage identification equation of piles was deduced using the structural vibration equation. The equation contained three major factors: change rate of element modal strain energy, damage factor of pile, and sensitivity factor of modal damage. The sensitive modals of damage identification were selected by using sensitivity factor of modal damage firstly. Subsequently, the indexes for early-warning of pile damage were established by applying the change rate of strain energy. Then the technology of computational analysis of wavelet transform was used to damage identification for pile. The identification of small damage of pile was completely achieved, including the location of damage and the extent of damage. In the process of identifying the extent of damage of pile, the equation of damage identification was used in many times. Finally, a stadium project was used as an example to demonstrate the effectiveness of the proposed method of damage identification for piles. The correctness and practicability of the proposed method were verified by comparing the results of damage identification with that of low strain test. The research provided a new way for damage identification of piles.
Journal Article
Materials and structures under shock and impact
In risk studies, engineers often have to consider the consequences of an accident leading to a shock on a construction. This can concern the impact of a ground vehicle or aircraft, or the effects of an explosion on an industrial site. This book presents a didactic approach starting with the theoretical elements of the mechanics of materials and structures, in order to develop their applications in the cases of shocks and impacts. The latter are studied on a local scale at first. They lead to stresses and strains in the form of waves propagating through the material, this movement then extending to the whole of the structure. The first part of the book is devoted to the study of solid dynamics where nonlinear behaviors come into play. The second part covers structural dynamics and the evaluation of the transient response introduced at the global scale of a construction. Practical methods, simplified methods and methods that are in current use by engineers are also proposed throughout the book. The aim of this book is to present theoretical elements regarding solids and structures, as well as modeling tools in order to study the vulnerability of a structure to a short duration action, generally of accidental nature. The book takes the point of view of an engineer seeking for the modeling of the physics at stake to relevantly carry out his study. The book originality is that it gathers elements from various fields of engineering sciences, for the purpose of a practical objective.
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