Effect Of Restraint Research Articles

Effects of Base Course Restraint on Early Age Transverse Cracking in CRCP

Asphalt Interlayer (AIL) is planning to be inserted between a concrete slab and base course in continuously reinforced concrete pavement (CRCP) in a super express highway in Japan. In this study, the effects of AIL are investigated based on observations and measurements on a test CRCP and simulations with three dimensional finite element method (3DFEM). The test pavement has two sections with and without AIL and strains and temperatures in the slab were measured. Investigation of the test pavement revealed that air temperature at the time of concrete casting affected the strains in the slab and crack pattern. Also, three closely spaced cracks were observed in the AIL section. To examine how AIL affects cracking situations, numerical simulations were conducted using a 3DFE model that was developed in this study. The model employs an incremental algorithm to consider changes of free contraction strain (FCS) and material properties of concrete at the early age. Mechanical interaction between steel and concrete was modeled with three nonlinear springs. The model was validated by simulating early age cracking of the slab and comparing the predicted strains and the strains measured in the test pavement. Effects of AIL on spacing and width of transverse crack were investigated with the model. The simulations of the 3DFE model revealed that the crack spacing does not change by using AIL, while AIL narrows the crack width. It was found that a small peak in tensile stress on the top of the slab near the crack appears in the AIL section, which might cause “secondary” crack near “primary” crack. The peak disappears after the secondary crack occurs near the primary crack, resulting in a cluster cracking observed in the test pavement.

Methodology for Establishing Permanent Curl/Warp Temperature Gradients in Jointed Plain Concrete Pavements

Jointed plain concrete pavements curl due to temperature gradients and warp in the presence of drying shrinkage gradients. Since this deformation is restrained by factors, such as the slab self-weight, tensile stresses are generated. Slabs do not remain flat in the absence of daily gradients. This is due to the presence of permanent gradients in the slab. A portion of the permanent gradients is the temperature gradient that exists in the slab at the zero-stress time. The gradient present at the zero-stress time, known as built-in, locks into the slab, shifting the curling due to transient gradients up or down. The other component included in the built-in gradient is the permanent warp that develops due to irreversible drying shrinkage. The built-in gradient is reduced over time due to creep. A procedure is established in the study for defining the built-in gradient in the slab. First, the zero-stress time is established, so that the built in temperature gradient can be identified. This is performed using the data from four instrumented pavement sections in Western Pennsylvania. A temperature/hydration model is used to predict the temperature and degree of hydration within the pavement structure based on the ambient temperature and concrete mixture design. Next, the component of the built-in gradient attributed to irreversible drying shrinkage is determined. This is achieved by using long-term strain measurements in an instrumented pavement section in Pennsylvania, as well as two instrumented sections at the Minnesota Road Research Facility (MnROAD). The unrestrained drying shrinkage is then predicted using a numerical relative humidity model. The difference between the predicted and measured drying shrinkage is attributed to the effects of creep and base restraints. The temperature gradient at the zero-stress time is then added to the irreversible drying shrinkage component to obtain the total built-in gradient.

Determination of Strain and Stress Field in Screening Test for Concrete Fire Spalling-Passive Restraint Effect.

The paper examines the impact of passive restraint on fire-induced spalling in concrete, utilizing a concrete mixture to minimize compositional variability. A variety of specimen geometries was prepared, including standard cubes and cylinders for the determination of mechanical properties and slabs of different dimensions for fire spalling tests conducted under controlled conditions. A top-opening Dragon furnace, which applies ISO 834-1 fire curves, was used to evaluate the influence of "cold rim" boundaries, where slab edges were insulated to create thermal restraint. The cold rims were categorized as 0 cm, 10 cm, and 20 cm, with each modification representing a different degree of thermal expansion restraint. Digital image correlation (DIC) was utilized to monitor the strain fields on the unheated slab surfaces. The findings demonstrated that increasing the cold rim width implies a rise in compressive stress and strain in the central zone, thereby precipitating a more pronounced spalling behaviour. The unrestrained slabs (cold rim 0 cm) exhibited minimal spalling, whereas the restrained slabs (cold rim 20 cm) demonstrated significant spalling depths and volumes. The study confirms that thermal dilation restraint intensifies the severity of spalling and provides a quantitative framework that links stress evolution, strain distribution, and spalling depth. The findings emphasize the necessity of managing thermal restraint to properly assess fire-induced concrete spalling in material screening tests.

What makes the synergy between pollution and carbon emission control effective? Based on an evaluation of the carbon emissions trading pilot policy

Abstract To accomplish clean air and carbon peaking and neutrality goals in the new development stage, it is essential to synergize air contamination and carbon emission reduction. This research assesses the synergistic effect between air contamination and carbon emission reduction of the carbon emissions trading (CET) pilot policy in China using the difference-in-differences (DID) model. The results demonstrate that, first, this policy has a dual impact by considerably reducing both carbon emissions and PM2.5 emissions. Second, the pilot policy can decrease carbon emissions through "pollution-to-carbon" synergistic control effect, which enables the incentive and restraint functions to be strengthened for trading carbon emissions. Nevertheless, the synergistic control effect of "carbon-to-pollution" is not significant since the replacement effect produced by investment pressure. Third, the synergy between air contamination and carbon emission management in pilot areas substantially reduces pollution emissions, suggesting that a greater degree of synergistic control generates more effective incentive or restraint effect.

Effects of Head Restraints on Radial Thermal Responses of an Energy Pile Embedded in Cohesive Soil

Effects of Head Restraints on Radial Thermal Responses of an Energy Pile Embedded in Cohesive Soil

Punching shear performance of reinforced flat slabs considering in-plane restraints under and after a fire

Two full-scale test specimens, a reinforced concrete reference slab (denoted as S1) and a polypropylene fibre (PPF) concrete slab (S2), with a PPF length of 3 mm and PPF dosage of 1.0 kg/m3, were designed to investigate the effects of the in-plane restraints and PPF admixture on the punching shear response of flat slabs under and after a fire. The results indicated that both S1 and S2 showed a clear trend toward punching shear failure at approximately 210 min after ignition, but S2 had smaller crack widths and a greater limit displacement owing to the PPF admixture. Because of the restrained thermal expansion, many radial cracks first appeared around the punching shear cones on the top surfaces of S1 and S2 and then gradually extended across nearly the entire top surfaces of both test slabs, including their four corners. Meanwhile, both test slabs experienced cracks, which expanded and then retracted under a fire owing to in-plane restraints. In the residual load-carrying capacity tests, both S1 and S2 experienced larger ultimate destructive loads than the unrestrained slabs; thus, the in-plane restraints significantly improved their residual bearing capacities. In addition, S2 experienced a lower residual load and larger plastic deformation owing to the PPF admixture, which exhibited certain ductile failure characteristics.

Effects of head restraint (HR) interference on child restraint system (CRS) performance in frontal and far-side impacts.

Forward-facing child restraint systems (FF CRS) and high-back boosters often contact the vehicle seat head restraint (HR) when installed, creating a gap between the back surface of the CRS and the vehicle seat. The effects of HR interference on dynamic CRS performance are not well documented. The objective of this study is to quantify the effects of HR interference for FF CRS and high-back boosters in frontal and far-side impacts. Production vehicle seats with prominent, removeable HRs were attached to a sled buck. One FF CRS and two booster models were tested with the HR in place (causing interference) and with the HR removed (no interference). A variety of installation methods were examined for the FF CRS. A total of twenty-four tests were run. In frontal impacts, HR interference produced small but consistent increases in frontal head excursion and HIC36. Head excursions were more directly related to the more forward initial position rather than kinematic differences caused by HR interference. In far-side impacts, HR interference did not have consistent effects on injury metrics. Overall, these results suggest only slight benefits of removing the HR in frontal impacts specifically. Caregivers should use caution if removing a vehicle HR to ensure that the current child occupant and all future vehicle occupants have adequate head support available in case of a rear impact.

Effect of reinforcement on the anisotropic expansion of concrete with CSA-based expansive additives

Expansion properties of concrete with expansive additives (EAs) are dependent on the composition of the EAs and the nature of the external restraints. This study focuses on calcium sulfoaluminate (CSA) based EA, investigating their expansion behavior under uniaxial restraint conditions. This novel aspect of the work is highlighting the effect of restraint in one direction on the expansion in different directions (i.e. restraint and stress-free directions) as well as the overall volumetric expansion of concrete. The current work also compares the anisotropic expansion of concrete with CSA-based EA to the free lime-based EA. Experimental results reveal that the expansion of concrete in the restraint direction significantly reduces inducing stress in the concrete, while the other directions remain unaffected by the degree of restraint. The study introduces an anisotropic coefficient to quantify the effect of external restraint on expansion, showing a higher coefficient for CSA-based EA compared to free lime-based EA under similar restraint conditions. This study provides insights into the complex interplay between external restraint and expansion characteristics for CSA-based EA concrete.

Restraint effect of steel bar on early-age shrinkage of steel bar-mortar composites

Time-space-dependent stress and strain distribution within steel bar-mortar composites is key for shrinkage and cracking prediction of Reinforced-Concrete (RC) members. A novel system was designed to investigate the restraint of steel bars on the early-age shrinkage while digital image correlation was also employed to analyze spatial strain distribution. The measured restraint degree increases with the reinforcement ratio and maintains stable after about 36 h. Restraint effects is interfered by micro-cracks, because of which the calculated restraint degree matched the measured one better after being modified by a coefficient concerning reinforcement ratio. The overall restrained stress shows a three-stage process affected by the bonding evolution. The strain spatially undergoes a three-region distribution along the steel bar induced by the shear transfer and a two-region distribution on the cross-section aligning with the interface gradient. This study demonstrates a quantitative analysis on the steel bars restraint parameters and its evolution.

Organizational factors associated with less use of restraints in older adults with dementia in acute care hospitals: A scoping review.

Dementia affects more than 55 million people worldwide. Use of restraints for hospitalized older adults with dementia is a social issue that should be addressed systematically and should not depend on the characteristics of nurses. This study reviewed the literature on organizational factors associated with reducing use of restraints in older adults with dementia admitted to acute care hospitals. A scoping review was performed. Three databases were searched for papers that met our eligibility criteria. Factors related to restraint reduction were extracted, and results were deduced. Through inductive analysis, subthemes were categorized according to similarities and differences, which were then integrated into broader themes. Sixteen studies were eligible for inclusion. The prevalence of restraints ranged from 5.1% to 80.0% depending on how the meaning of restraint was interpreted. The most common indications for restraints were history of falls and fall risk. Interdisciplinary screening for restraints was associated with reduced prevalence of restraints, with a 0.18-fold (confidence interval [CI]: 0.12-0.24) reduction through use of a restraint decision flowchart and a 0.76-fold (CI: 0.63-0.92) reduction through consultation with a psychiatrist. Interdisciplinary members included nurses, physicians, clinical psychologists, pharmacists, respiratory therapists, and therapists. Research is needed to introduce and develop an interdisciplinary restraint decision-making system and to test its effectiveness. Important factors in implementing alternatives to restraints are the harmful effects of restraints, expertise in dementia, regular education on alternative methods, an inpatient environment that ensures patient safety, and the development of human resources.

Enhancing reliability in laser powder bed fusion through substrate modification: microstructure, mechanical properties and residual stress

Laser additive manufacturing (LAM) is prone to excessive tensile residual stresses, leading to cracking or even failure, seriously hindering its wide application. Therefore, controlling residual stress to avoid crack formation and improve forming quality is crucial for reliable LAM. Most of the past research controls the residual stresses by modifying the process during the forming process, which is a very complicated method. In this study, through alterations in the form of a substrate to modify its restraint effect on the resulting structure and heat dissipation channels, the impact of them on the microstructure, defects, residual stress, and fracture characteristics to mitigate the likelihood of cracking in laser powder bed fusion (LPBF) was systematically studied. The results showed that the microstructure of all the specimens consists of fine dendritic, cytosolic, and columnar. Specimens with un-grooved substrates exhibited more holes and cracks, and solidification cracks were predominant. The crack density in specimens with grooved substrates was reduced by 71 %, reaching a relative density of 98.94 %. Tensile test results showed that the mechanical properties of the grooved specimens were excellent, with the tensile strength and yield strength higher than the un-grooved samples by 29 MPa and 11.7 MPa, respectively. And the results of the residual stresses indicated significantly lower tensile residual stresses in specimens with grooves, due to reduced restraint stresses and increased heat dissipation, mitigating the extent of crack propagation. These findings provided a simpler new approach to LPBF of crack-free components with excellent mechanical properties.

Numerical Study on the Axial Compression Behavior of Composite Columns with High-Strength Concrete-Filled Steel Tube and Honeycombed Steel Web Subjected to Freeze–Thaw Cycles

To investigate the axial compression behavior of composite columns with high-strength concrete-filled steel tube flanges and honeycombed steel web (STHHC) under load during freeze–thaw cycles, 48 full-scale composite column specimens were designed with different parameters: the restraint effect coefficient (ξ), concrete strength (fcu), number of freeze–thaw cycles (nd), slenderness ratio (λ), space–height ratio (s/hw), and hole–height ratio (d/hw). The finite element models of STHHC composite columns were simulated using ABAQUS finite element software (Version: 2021). The modeling method’s rationality was verified by comparing simulation results with experimental outcomes. Based on the finite element model, a parametric analysis of the composite columns under freeze–thaw cycles was conducted, analyzing their failure modes and load-bearing processes. The results indicate that the bearing capacity of the STHHC increased with increases in ξ and fcu, and decreased with a rise in λ. In contrast, the influence of s/hw and d/hw on the ultimate bearing capacity of the composite columns was relatively minor. An equation for calculating the axial bearing capacity of the STHHC composite columns under freeze–thaw cycles was derived using statistical regression methods and considering the impact of different parameters on the axial compressive performance of the composite columns, laying the foundation for the promotion and application of this type of composite column in practical engineering projects.

Alcohol use, civilian interference, and other possible risk factors for death during restraint

Physical restraint is usually used when trying to control and terminate a violent episode. Many causes are possible behind aggressive, agitated, and violent behavior. Some of these are such factors that can either be detected in forensic autopsies or can be evident from the person's medical records. Various causes for deaths during physical restraint have been suggested.In this study, we wanted to review all incidents in which physical restraint was employed, ending in death of the restrained person, whether the restraint was applied by police officers, security guards, police custody personnel, health care personnel or ordinary civilians. The main aim was to see if this new kind of study design would increase our knowledge in circumstances and causes leading to death in restraint situations.Data was collected retrospectively from all forensic autopsies performed in the Southern Finland area during 2010–2015. We went through 21,036 forensic autopsy cases and found 12 cases (0.06 %) in which a physical restraint was employed before death. Police officers were involved in the physical restraint in 7/12 of the cases: in two of these cases, police alone; in three cases, police and guards; and in two cases, police and health care personnel. Civilians carried out the restraint in 5/12 cases. With civilians responsible for the restraint, the cause of death was more likely considered to be a result of the restraint itself than in cases where police and other authorities were responsible for the restraint. This could be because civilians aren't educated about safe restraint methods, and they might themselves be intoxicated. Alcohol was the most common psychoactive substance found in this study and could be a risk factor for not only aggressive behavior but also death, since alcohol use can provoke cardiac arrhythmias and even sudden death. Based on this study, and previously published studies, we see restraint deaths as a varying spectrum of deaths, in which the death is often possibly a result of many factors, including the effects of agitation and restraint, intoxication, and cardiac and other illnesses.

Component tests and numerical simulations of 3D steel frame structures for progressive collapse

This paper presents a comprehensive study on three-dimensional steel frame structures subjected to progressive collapse, drawing insights from a full-scale steel frame substructure test. The investigation encompasses connection component tests and numerical simulations, focusing on extended end plate and double-angle cleat connections employed in the substructure test. The mechanical properties of the connection components were tested, forming a basis for defining component properties in subsequent connection models. Finite element (FE) models of the test substructure were developed, utilizing hybrid elements for the steel frame part, which include beam, connector, and spring elements based on the component method. To simulate reinforced concrete slabs, a combination of refined solid elements and simplified shell elements was employed. The former accurately captures detailed failure modes, while the latter efficiently simulates the collapse behavior of large-scale steel frame structures. Validation of the established models against test results encompassed load-displacement responses, internal forces in structural members, and failure modes. The validated FE models were then utilized to analyze and discuss the contributions of various structural components in resisting progressive collapse. Specific focus was placed on the development of load-resisting mechanisms in the floor slab and the influence of beam-column connection types on structural behavior. The paper explores the role of bracing systems in a building in resisting progressive collapse. Additionally, it evaluates the effectiveness of the restraint systems used in the test, shedding light on their ability to accurately reflect real restraint effects from the surrounding structure. The findings presented herein contribute valuable insights to the understanding of progressive collapse behavior in steel frame structures, with implications for robustness design of multi-story steel buildings.

EFFECTS OF SHORT-TERM PHYSICAL RESTRAINT ON RECTAL TEMPERATURE AND RESPIRATORY RATE OF THE AFRICAN GIANT RAT (Cricetomys gambianus, WATERHOUSE) IN ZARIA

Study was carried out on 28 African giant rats (AGRS) of both sexes, with the aim of determining the effect of short-term physical restraint on rectal temperature (RT) and respiratory rate (RR). The results showed graded increases (P < 0.01) in RT of 0.13°C, 0.18°C and 0.28°C, after 1 minute, 3 minutes and 5 minutes of restraint, respectively. The RR showed no difference before and after the restraint. There was no sex difference (P > 0.05) in the responses. In conclusion, short-term physical restraint caused time- dependent graded increases in RT, which may confound thermoregulatory studies that involve restraint of AGRS.

Experimental and Numerical Study on the Anchoring Mechanism of an Anchor Bolt Considering its Lateral Restraint Effect

Experimental and Numerical Study on the Anchoring Mechanism of an Anchor Bolt Considering its Lateral Restraint Effect

Restraint effect of partition wall on the tunnel floor heave in layered rock mass

Restraint effect of partition wall on the tunnel floor heave in layered rock mass

Experimental and numerical investigation on short CHS steel columns restrained with HFRP under axial compressive loading

Fiber-reinforced polymer (FRP) is a practical approach to delay or even suppress the deformation of steel structures. However, their application has been constrained by brittle damage and low strengthening efficiency. This paper presents an investigation of the mechanical behavior of short circular hollow section (CHS) steel columns restrained with hybrid fiber-reinforced polymer (HFRP) composed of carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP) under axial compression. The results show that the restraint effect of HFRP composed of one layer of transverse CFRP as the middle layer and two layers of transverse GFRP as the inner and outer layers is better than two layers of transverse CFRP, with peak load and ductility increased by 7.29 % and 12.36 % over the latter. Then, a simplified method for simulating HFRP and single FRP restrained short CHS steel columns is proposed and verified by experimental results. Moreover, a parametric study is performed to discuss the effect of the diameter-to-thickness ratio on the bearing capacity. Finally, a universal method is proposed to calculate the ultimate bearing capacity of HFRP and single FRP restrained short CHS steel columns, for which the average error and standard deviation from the measured values are 2.27 % and 0.024, respectively.

Comparison of the Effects of Postoperative Arm Restraints and Mittens on Cleft Lip Scar Quality after Primary Repair.

Introduction: Postoperative management following primary cleft lip repair varies across institutions, cleft care teams, and individual surgeons. Postoperative precautions employed after cleft lip repair include dietary restrictions, pacifier limitations, and immobilization, with arm restraints long being used. Yet, restraint distress has led to the exploration of other forms of immobilization. Thus, this study aims to assess cleft lip scar quality and complication rates after postoperative immobilization with arm restraints versus hand mittens. Methods: A retrospective review of patients with unilateral cleft who underwent primary repair with the senior surgeon was done. Data on demographics, surgical characteristics, and immobilization utilized were gathered. A survey with pictures of postoperative scars were sent to laypeople who assessed scar quality with Modified Scar-Rating Scale scores for surface appearance, height, and color of the scar tissue. Statistical analysis was carried out for significance. Results: Twenty-eight patients with a unilateral cleft underwent arm restraints after primary lip repair, and twenty-seven utilized mittens. In total, 42 medical students completed the scar assessment. Photographs were taken an average of 23.9 (±5.8) and 28.2 (±11.9) months postoperatively in the restraint and mitten groups, respectively (p = 0.239). There were no statistically significant differences in scores between scar surface, height, color, or overall scar appearance. Complication rates were also similar between groups. Conclusions: Arm restraints appear to have no additional benefit relative to scar quality, as compared to mittens. Considering the arm restraints' burden of care, mittens should be considered as a measure to protect the lip after primary repair.

A physically consistent 2D residual stress model for approximating 3D effects in welding

Welding-induced residual stresses play a critical role in fitness-for-service evaluation of pressure equipment as stipulated by codes and standards, e.g., BS 7910 and API 579 RP-1/ASME FFS-1. Due to the complex residual stress evaluation process, two-dimensional (2D) residual stress modeling is most often exercised for supporting the development of the residual stress prescriptions in these FFS codes. Two major limitations exist in such a 2D modeling approach. One is the lack of heat sink effects in the third direction, resulting in a missing linkage to the actual welding linear heat input. The other is the over-simplifications of the mechanical restraint effects on the residual stress development process by imposing generalized plane-strain or axisymmetric conditions. This paper presents a physically consistent 2D residual stress model, with which actual welding linear heat input can be consistently interpreted for use in a 2D thermal model and 3D mechanical restraint effects can be approximated through a set of closed-form expressions that can be readily implemented in available finite element procedures. The effectiveness of the proposed 2D modeling procedures is then validated against a few well-documented residual stress case studies on which experimental data are available.