Detachment analysis of dehumidified repair mortars applied to historical masonry walls

An innovative laboratory procedure for the pre-qualification of repair mortars is described. The tested mortars are suitable for use with new dehumidified plasters applied to historical masonry walls. Long-term plaster detachment frequently occurs because of the mechanical incompatibility of mortar. The procedure consists of the application of static loads to mixed stone block-mortar specimens with particular characteristics, in terms of geometry and adhesion at the interface. A numerical simulation based on the cohesive crack model was used to follow the experimental data, in order to describe the evolutionary phenomenon of detachment as a function of a small number of parameters. The methodology is currently being used at Sacro Monte di Varallo Special Natural Reserve (UNESCO heritage site) in Piedmont (Italy

Dynamic Effects of Turbulent Crosswind on the Serviceability State of Vibrations of a Slender Arch Bridge Including Wind-Vehicle-Bridge Interaction

The use of high-performance materials in bridges is leading to structures that are more susceptible to wind- and traffic-induced vibrations due to the reduction in the weight and the increment of the slenderness in the deck. Bridges can experience considerable vibration due to both moving vehicles and wind actions that affect the comfort of the bridge users and the driving safety. This work explored the driving safety and comfort in a very slender arch bridge under turbulent wind and vehicle actions, as well as the comfort of pedestrians. A fully coupled wind–vehicle–bridge interaction model based on the direct integration of the system of dynamics was developed. In this model, the turbulent crosswind is represented by means of aerodynamic forces acting on the vehicle and the bridge. The vehicle is modeled as a multibody system that interacts with the bridge by means of moving contacts that also simulate road-surface irregularities. A user element is presented with generality and implemented using a general-purpose finite-element software package to incorporate the aeroelastic components of the wind forces, which allows modeling and solving of the wind–vehicle–bridge interaction in the time domain without the need for using the modal superposition technique. An extensive computational analysis program is performed on the basis of a wide range of turbulent crosswind speeds. The results show that bridge vibration is significantly affected by the crosswind in terms of peak acceleration and frequency content when the crosswind intensity is significant. The crosswind has more effect on the ride comfort of the vehicle in the lateral direction and, consequently, on its safety in terms of overturning accidents

Quantum Smoluchowski equation: Escape from a metastable state

We develop a quantum Smoluchowski equation in terms of a true probability distribution function to describe quantum Brownian motion in configuration space in large friction limit at arbitrary temperature and derive the rate of barrier crossing and tunneling within an unified scheme. The present treatment is independent of path integral formalism and is based on canonical quantization procedure.Comment: 10 pages, To appear in the Proceedings of Statphys - Kolkata I

Single-Leg Dynamic Balance Training to Improve Stability on Post ACL Reconstruction

ACL injuries are a prevalent concern, particularly in athletic populations, leading to significant research efforts aimed at effective treatment and prevention. Previous studies indicate that while surgical reconstruction is common, a considerable percentage of patients do not regain pre-injury sports performance. This highlights the necessity for enhanced rehabilitation strategies focusing on dynamic balance and neuromuscular control. The study involved 90 participants were divided into three groups: a control group receiving conventional ACL rehabilitation. Conventional Rehabilitation, involving muscle strength and endurance exercises, such as stationary biking, straight leg raises, step-ups, hamstring curls, toe raises, partial squats, and wall squats. Single-Leg Dynamic Balance Training, implemented in two stages over six weeks, incorporating modified Romberg exercises, retro walking, balance board exercises, plyometric exercises, and isometric as well as isotonic strengthening exercises for the quadriceps, hamstrings, and hip muscles. The experimental group showed significant improvements in both joint position sense and SEBT scores compared to the control group. Statistical analysis revealed that the joint position sense increased significantly from 25.4 ± 4.91 to 14.93 ± 5.22 (t = 6.653833) in the experimental group, whereas the control group exhibited minimal changes. Similarly, SEBT scores improved significantly in the experimental group from 77.46 ± 5.81 to 70.4 ± 2.29 (t = 6.33956), highlighting the effectiveness of the dynamic balance training. Single-leg dynamic balance training significantly enhances knee stability post-ACL reconstruction. These findings underscore the potential benefits of incorporating targeted balance training into ACL rehabilitation programs to improve patient outcomes and reduce the risk of re-injury

Numerical dynamic analysis of stiffened plates under blast loading

Using the general purpose finite element package Abaqus, an investigation has been carried out to examine the dynamic response of steel stiffened plates subjected to uniform blast loading. The main objective of this study is to determine the dynamic response of the stiffened plates considering the effect of stiffener configurations. Several parameters, such as boundary conditions, mesh dependency and strain rate, have been considered in this study. Special emphasis is focused on the evaluation of midpoint displacements and energy of models. The modeling techniques were described in details. The numerical results provide better insight into the effect of stiffener configurations on the nonlinear dynamic response of the stiffened plates subjected to uniform blast loading

Mechanical Behavior of Steel Pipe Bends; An Overview.

An overview of the mechanical behavior of steel pipe (elbows) is offered, based on previously reported analytical solutions, numerical results, and experimental data. The behavior of pipe bends is characterized by significant deformations and stresses, quite higher than the ones developed in straight pipes with the same cross section. Under bending loading (in-plane and out-of-plane), the main feature of the response is cross-sectional ovalization, which influences bending capacity and is affected by the level of internal pressure. Bends subjected to cyclic in-plane bending exhibit fatigue damage, leading to base metal cracking at the elbow flank. Using advanced finite-element tools, the response of pipe elbows in buried pipelines subjected to ground-induced actions is also addressed, with emphasis on soil-pipeline interaction. Finally, the efficiency of special-purpose finite elements for modeling pipes and elbows is briefly discussed. © 2016 by ASME