Opening Size Research Articles

Global stability capacity of partially encased composite columns with cruciform-shaped section under axial compression

This paper undertakes a test investigation and finite element (FE) analysis of the stability behavior of partially encased composite (PEC) columns with cruciform-shaped sections. Two PEC column specimens with the same geometric size were tested under axial compression loading, and the difference between the specimens is that the main steel components (MSCs) made of solid-web steel and castellated steel, respectively. The test results show that the two columns exhibited similar failure modes: concrete crushing and global flexural instability. Furthermore,the capacities of both columns were found to be smaller than the corresponding theoretical axial capacities of the composite column section. The test and FE results show that the bearing capacity of the PEC columns with solid-web MSCs is higher than that of the PEC columns with castellated MSCs. The size of the web openings exerts a considerable detrimental impact on the compressive capacity of the PEC column, while the shape and spacing of the openings have little influence on the capacity. In addition, design equations were proposed to predict the stability capacity of the cruciform-shaped section PEC column with both solid-web MSCs and castellated MSCs, in the equations, the castellated MSCs were simplified as the lattice columns with batten plates.

Comparing Optimized Sound Absorption Coefficient of Aluminum Foam with Local Search Algorithm, Genetic Algorithm, and Particle Swarm Optimization

Introduction: The principle of passive sound control is based on the phenomenon of sound absorption by absorbers. The factors affecting sound absorption include porosity, pore size, pore opening size, thickness, and air flow resistance. Materials and methods: In this study, the authors compared the optimization results of the effective parameters on sound absorption coefficient (AC) using the three optimization methods: Guided Local Search (GLS), Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The programming was done in MATLAB software. Thicknesses of 5, 10, 20, 30 and 40 mm were chosen for optimization at frequencies of 500 to 3000 Hz. Results: In frequencies above 2 kHz (thickness 5 to 40 mm), the three optimal methods had the same performance and estimated AC of 1. At low frequencies of 2 kHz and thicknesses of 30 and 40 mm, GA and PSO methods obtained an AC of 1. Conclusion: It seems that the GA and PSO optimization algorithm are suitable methods to optimize the AC of metal foam in low and high frequencies.

Drivers of international fiscal spillovers

AbstractThis paper investigates the drivers of international fiscal spillovers across 62 countries for the period covering 1970–2021. Using the local projections method at the country‐pair level, fiscal spillovers are estimated as the cumulative response of the real gross domestic product (GDP) growth in spillover destination countries to a unit shock in the real government spending growth in spillover source countries. Pairwise estimation results (for 3782 country pairs) suggest that there are statistically significant fiscal spillovers for 36% of country pairs, whereas this ratio is 49% for country pairs within the euro area. For the median country pair, a unit shock of real government spending growth in the spillover source country results in about 0.09% of the increase in the real GDP growth of the spillover destination country, whereas this fiscal‐spillover estimate goes up to 0.42% when the spillover source is in the euro area, and the spillover destination is an oil producing country. A secondary investigation based on the Heckman selection model is used to identify the drivers of fiscal spillovers across country pairs, where the existence of statistically significant fiscal spillovers is shown to be connected to the proximity between countries. The size of fiscal spillovers is further shown to increase with the initial (as of 1970) country size, trade openness, and government size of the spillover source country, whereas it decreases with the initial country size and trade openness of the spillover destination country. Important policy suggestions follow.

Numerical Analysis of Corrugated Castellated Beam with and Without Openings

The construction industry is constantly seeking innovative solutions to optimize the performance and efficiency of structural elements. Castellated beams with corrugated webs have emerged as a promising option in this pursuit. Their unique geometry, including web holes, makes estimating shear load capacity different from traditional beams with solid webs. These beams are becoming increasingly popular in engineering and economics due to their advantages. The openings in the web can take various shapes, as detailed in the research paper, which compares the load versus deflection for castellated beams with rectangular and hexagonal openings, analyzed using the software ABAQUS® CAE. The trapezoidal corrugated web configuration notably augments the beam's resistance to buckling failure and furnishes superior resistance to buckling compared to a plain web beam. Predominant factors impacting the efficacy of castellated-corrugated web beams encompass the overall beam height and the size of the web opening. The study conducts a comparative analysis of the ultimate load-bearing capability of these beams about both plain and corrugated web beams. Moreover, the manuscript advances an original technological proposal entailing the integration of a trapezoidal-shaped web into a castellated beam. The load-bearing capacity of castellated beams with various web opening shapes, such as rectangles and hexagons, was contrasted with that of the I beam. Among these shapes, hexagon web opening TWHC has higher Material savings with an increase of 13 % compared to the I beam. The results detail that the corrugated web rectangular castellated beams have less weight and more strength than the corrugated web hexagon castellated beam.

RS-AAT for enhancing saturation and chloride resistance in unsaturated concrete: Experimental and numerical assessment

In this paper, the effect of RS-AAT (Reverse-seepage and Saturation based Active Anti-corrosion Technology) on chloride ion erosion and saturation of unsaturated concrete is studied. The design of partially opening of permeable pipes is proposed for partial purpose. The infiltration of chloride ions in cylindrical concrete by RS-AAT is experimentally and numerically analyzed. Based on the water vapor adsorption and adsorption isotherm test and chloride ion erosion test, a convection-diffusion model of chloride ions with varying saturation is established by using simultaneous V-G model and Richards' equation. It can be used for characterizing the effect of pore opening on saturation change and chloride ion erosion. The results show that the use of RS-AAT can accelerate the growth of concrete saturation in the alternating wet and dry zones, and keep the area in a saturated state, under the effect of reverse seepage and saturation, the durability of the structure is increased. Moreover, the opening size and spacing of the permeable pipe are especially investigated. The results recommend 8 mm opening diameter and 2 mm opening spacing, by which the opening spacing is reduced as much as possible, and the ability to resist chloride ion erosion for a long time can be improved s under the combined action of reverse seepage and saturation. The significance of these results is immense for the continued utilization of the novel anti-chloride attack technology in engineering applications.

Association of Timing With Postoperative Complications in the Management of Open Distal Radius Fractures

Background: This study investigates whether open distal radius fractures (ODRFs) treated after 24 hours from time of injury have an increased risk of infection or overall complication profile compared with those treated within 24 hours. Methods: Retrospective review was performed of all patients treated for ODRF over a 6-year period at a single large academic institution. Postoperative complications included surgical site infections, need for revision irrigation and debridement, delayed soft tissue healing, loss of reduction, nonunion, and malunion. Results: One-hundred twenty patients were treated for ODRF. Mean (SD) age at time of injury was 59.92 (17.68) years. Twenty patients (16.7%) had postoperative complications. Regarding mechanism of injury, 78 (65.0%) had a low-energy and 42 (35.0%) had a high-energy injury. Age and fracture grade were not significant factors. Mean (SD) open wound size was 1.18 (1.57) cm. Mean (SD) time from injury presentation to the emergency department (ED) and first dose of intravenous antibiotics was 3.07 (4.05) hours and mean (SD) time from presentation to the ED and operative treatment was 11.90 (6.59) hours, which did not show a significant association with postoperative complications. Twenty-four patients (20.0%) were treated greater than 24 hours after presentation to the ED, which was not significantly distinct from those treated within 24 hours. Conclusion: Patients with ODRFs treated after 24 hours were not associated with a greater risk of postoperative complications. Factors including age, energy and mechanism of injury, and fracture grade did not alter outcome in any statistically significant manner. Level of Evidence: Level IV

Experimental investigation on thermal radiation of compartment fire under fuel-controlled condition

Due to the serious adverse thermal impact on adjacent rooms and buildings, compartment fire is one of the very important topics in fire research. While for the thermal radiation of compartment fire, there are few related studies with a lack of thermal radiation models. This article experimentally studied the evolutions of radiation heat flux of compartment fire under fuel-controlled condition. Experiments were carried out employing a reduced-scale compartment with a wall opening whose size can be adjusted. The radiant heat flux (RHF) from compartment fire received by target object was measured and analyzed for various opening sizes, fuel supply rates, horizontal distances and vertical heights, and a total of 180 test data were considered. Results showed that with the increasing horizontal distance between the target object and the compartment opening, the RHF decreased rapidly at first and then decreased gradually. The view factor of the opening toward the target object was analyzed, which was related to the opening size, the horizontal distance and vertical height. The view factor exhibited an evolution pattern of the first rapidly decreasing and then slowly decreasing with horizontal distance, which was similar to the RHF received by the target object. Then, based on the view factor, the radiation model related to the opening dimension and temperature inside compartment was proposed to calculate RHF received by target object, which was proved to be in good consistency with experimental data.

The critical discontinuity of vertical temperature distribution along window opening height from intermediate-scale compartment fire

The fire plume spilled from a window is believed to be one of the main fire sources with respect to a building façade fire, which happened previously in China. To have a deep understanding of vertical temperature distribution at window opening is of significance. In the current contribution, a series of compartment fire tests under over-ventilation were conducted with a 1.35 m × 1.35 m × 1.35 m compartment to clarify the critical discontinuity position (HD) by varying window opening sizes, opening aspect and heat release rate (HRR). Temperature history at the window openings were recorded by a thermocouple net. A theoretical calculation method of HD is detailed according to the compartment configuration. It is found that the critical discontinuity area is observed apparently along the window opening height, which has a big temperature difference. By the comparison of experimental and theoretical results, the constant comprehensive coefficient of 1.68, 1.92 and 3.85 of 300 kW, 600 kW and 900 kW are got for an engineered empirical prediction model are proposed, respectively. It provides an insight for the understanding of critical temperature discontinuity and reference for engineering calculations.

An experimental and numerical study on two-way RC slabs with openings strengthened by ferrocement technique

This study investigates the impact of creating a central square opening on reinforced concrete slabs and assesses the strengthening process using ferrocement layers. The investigated key parameters were the opening sizes, type, number, and extension length (outside the opening sides) of steel mesh layers used to strengthen the tested slabs. The experimental program included the preparation and testing of twelve two-way reinforced concrete slabs with identical dimensions, thickness, and reinforcement, but were different with respect to opening sizes and strengthening schemes. Four slabs acted as control specimens without strengthening; one was solid; the other three had different opening sizes; and the other eight slabs were strengthened using a ferrocement layer of 2 cm thickness applied on the bottom of the slab around the openings with various reinforcement schemes which included the number, type, and extension length (outside the opening) of steel mesh. All slabs were supported along the four sides with a clear span of 1 m in both directions and tested under four-point loading. The test results demonstrate that creating an opening in the slab decreases the ultimate load by 21.5 %, 31.9 %, and 40.7 % for opening dimensions (15, 25, and 35 cm), respectively. Using the ferrocement strengthening method helps to increase slabs’ flexural load-carrying capacities and reduce crack propagation from opening corners. The study found that strengthening specimens with opening sizes of 15, 25, and 35 cm increased their flexural load-carrying capacities by 26 %, 33 %, and 34 %, respectively. The expanded steel mesh type also resulted in a higher ultimate load by 6–7 % than the welded mesh type. When the length of the strengthening ferrocement layers was doubled, the ultimate load went up by 6–7 %. Increasing steel mesh layer numbers from 1 to 4 increased the ultimate load by 25 % to 40 % compared to the corresponding un-strengthened slab with an opening. The maximum load of a slab with an opening was achieved by applying a 2 cm thickness of ferrocement layer reinforced with expanded metal mesh, with extension lengths equal to the opening's length. The study utilizes commercial software ABAQUS for finite element analysis (FEA) to validate the experimental results, resulting in a great agreement between the analysis and the experimental findings.

The Effect of Expansion Ratio, Opening Size, and Prestress Strand on the Flexural Behavior of Steel Beams with Expanded Web using FEA

The Effect of Expansion Ratio, Opening Size, and Prestress Strand on the Flexural Behavior of Steel Beams with Expanded Web using FEA

Numerical analysis of potential in electrostatic amplitude caused by paint splashing

In this research, the behavior of an electric field caused by the mechanism of electrostatic painting has been investigated using the finite element method and FLEXPDE software. The aim of this study is to optimize the electrostatic spraying performance of the paint sprayer by investigating the potential field in the paint nozzle. The results show that the potential and the electric field can be solved at any given point and displayed graphically. Additionally, changing the 2D rectangular covering surface to a circular one increased the potential value reached on the covering surface by 10 percent. The amount of electric potential and electrostatic field in the direction perpendicular to the x-axis is shown to be symmetrical and equal for y > 0 and y < 0. The size of the spray opening/hole is a significant factor in reaching paint particles to the coating surface. Doubling the size of the spray opening increased the potential value on the coating surface by 54.3 percent, while halving it decreased the potential value by 75 percent.

Reinforcement mechanism and the stress-strain behaviors of geocells made by non-woven geotextile

Geocell is one of the most widely employed geosynthetics for reinforcing soil beds across diverse applications, including base layer pavement and various structures such as embankments, foundations, and retaining walls. Its reinforcement mechanisms encompass both vertical and lateral cellular confinement, enhancing load distribution. Geocells are commonly made from polymer networks like high-density polyethylene (HDPE), non-woven geotextiles, and geogrids. Each type of geocell offers special advantages and effects on the reinforcement mechanism for the soil bed, dependent on material stiffness and effective opening size. This paper aims to assess both the reinforcement mechanism and stress–strain behavior of geocells (made by non-woven geotextile). To this end, three series of plate-loading tests were conducted on reinforced sand beds. The reinforcement configurations included single cells as well as multi-cells arranged in predetermined patterns. The experiments enabled us to determine bearing capacity, vertical surface displacement and axial strain of cell wall for different pocket sizes and numbers of cells. The results suggest that cells with pocket sizes matching the diameter of the loading plate exhibit superior performance. Furthermore, a comparative analysis between performance of single cells and multi-cells revealed that incorporating adjacent cells, particularly for geocells with smaller pocket sizes, significantly mitigates loading plate settlement. In addition, the results showed that the axial strain and deformation applied on non-woven geotextiles were more pronounced for smaller pocket sizes than for cells with larger pocket sizes.

Discussion of “Nondestructive measurement of the capillary water absorption coefficient and water transport behaviors of porous building materials by using single-sided NMR”

In February 2024, Construction and Building Materials published the paper “Nondestructive measurement of the capillary water absorption coefficient and water transport behaviors of porous building materials by using single-sided NMR”, which claims to measure the capillary absorption of moisture in brick, sandstone, mortar and concrete by means of moisture content profiling with the ‘NMR mouse’, a low-field, single-sided, open-magnet NMR instrument. This critique formulates several serious concerns on the study’s outcomes and conclusions. The excessively large similarity of the capillary absorption behaviour of the four materials is peculiar, since it disregards the differences in their open porosities and pore sizes. The overly large capillary moisture contents are equally abnormal, as they exceed the moisture storage limit of the material’s pore structure. There appears to be an inconsistency between the moisture content profiles and the overall moisture masses. Finally, it is shown that the lengthy time interval necessary for a single NMR pass limits the applicability of the NMR mouse for capillary absorption coefficients of porous building materials.

Thinking of Green, Low Carbon, and Energy-Saving Designs Based on the Variable Ventilation of Natatoriums: Taking the Jiading Natatorium of Tongji University as an Example

With the increasing demand for sports activities, sports architecture is flourishing. Creating a comfortable and healthy fitness environment while reducing energy consumption has become a focus for architects. Taking the Jiading Natatorium at Tongji University in Shanghai as an example, this study researched green energy in the variable ventilation of sports venues. The Autodesk Ecotect Analysis 2011 was used to conduct computational fluid dynamics (CFD) simulation analyses on four scenarios of opening and closing the swimming pool’s roof, with ventilation velocity as the primary evaluation indicator to assess the ventilation environment of each scenario. The relationship between the opening ratio of the roof and the ventilation environment of sports buildings was explored. The results showed that when the opening ratio is 37.5%, it achieves good ventilation effectiveness and avoids excessive wind pressure. The study also summarized six common forms of opening and closing roof structures and compared the differences in wind environments of different roof forms. The results indicated that the shape and opening ratio of the roof has a decisive impact on the distribution of indoor wind speed in buildings. Six optimal opening ratios for different roof forms in summer and suitable site conditions were summarized, providing a reference for the design and selection of swimming pool roofs. Furthermore, the wind speed distribution of different roof types showed a trend of gradually becoming uniform with the increase in opening area. However, the position of the wind speed peak is related to the form and size of the roof opening. This research provides valuable references for the low carbon and energy-efficient design of future swimming pool sports buildings.

Free convective heat transfer induced inside a vented duct having two aligned hot and cold cylinders: An experimental study

AbstractFree convective heat transfer created from two aligned cylinders immersed inside a vented air duct is experimentally investigated. The experiments include the measurements of cylinders temperature and the air temperature inside the enclosure under steady, turbulent, and incompressible flow properties by using steady‐state heat equations. The studied parameters include Rayleigh number (), opening sizes at lower and upper enclosure surfaces (), and space size between cylinders () with the constant ratio of enclosure width to cylinder diameter equal to 6. The findings displayed that the average air temperature inside the enclosure for the low values of S and O is low, and it rises as S is raised. The behaviors of Nu differ with changing Ra values. An interaction between hot cylinder and cold cylinder inside the enclosure is observed that depends on O and S values, and hence, they have a large impact on fluid temperature. The data indicated that rises with the for all and values. The value of for each cylinder depends on the values of and . The maximum value has been obtained when and with maximum enhancement between 30% and 50% depending on Ra values as compared with and , whereas the minimum average has been indicated when and . The profiles of reveal that , , and have a considerable influence on heat transfer.

Cyclic performance of RC frame joints with drilled openings

The construction industry commonly employs reinforced concrete (RC) beams with utility pipe openings to facilitate the passage of pipes through structures. These openings can be made through pre-construction or post-construction processes. Pre-construction openings in RC members are included in the design, and in most cases, designers include reinforcements around the opening to deal with the stress concentration and failure mechanism caused by the presence of the opening. However, post-construction or drilled openings are added after the structure is built, potentially disrupting established load paths, and developing stress concentrations that are not anticipated by the designer. In this study, three-dimensional nonlinear numerical finite element models (FEM) models were developed and validated according to four sets of experimental data. These models formed the basis for a parametric study exploring different design parameters. Parameters such as the width and depth of the specimen and the size of the opening were investigated. The results suggest that the presence of the opening leads to a brittle behavior and a sudden drop in the strength and stiffness of the specimen after the ultimate load. Increasing the depth of the beam results in more brittle behavior in specimens with openings and decreased the drift ratio where the specimen failed by up to 75%. However, increasing the width of the specimen increases the ductility of these specimens. Finally, opening size was found to lead the specimen to behave more brittle in all cases, and decrease the maximum drift ratio from 5% to 1.5%, and decrease the load capacity in 1.5% drift ratio by up to 61%. This study will help engineers and designers to understand the effect of beam-column joints with post-construction openings under cyclic loading, whether these openings are intentional or by human error.

Experimental and analytical investigation of opening effects on the in-plane capacity of unreinforced masonry wall

A test programme consisting of four half-scale URM walls was conducted under quasi-static cyclic loading to evaluate the negative influence of openings. Test results showed that the masonry adjacent to the opening experienced significant damage, and the specimens with a door opening was found to have complete detachment of the masonry pier, resulting in a reduction in the capacity of more than 25%. Furthermore, a detailed parametric nonlinear finite element analysis was performed to assess the influence of parameters affecting the in-plane load capacity of the URM wall. Numerical results showed that depending upon the size and location of openings and the material and geometric properties of walls, the in-plane load capacity was reduced by 6–82%. Considering the results of available experimental studies and present numerical analyses, a simplified equation was proposed to estimate the reduction in the in-plane load capacity of the specimen with different types of openings. The analytical study demonstrated that the proposed equation effectively provided reliable and consistent predictions of the strength reduction factor for walls with different types of openings.

Pig cesarean section, surgeries and feet work

In this session, we will discuss methods for bovine veterinar­ians to expand their services and offer surgical services to area show pig clients. The most common procedure will be a cesar­ean section on first parity females due to a decreased pelvic opening size or large fetal size or combination of both. The author will share our unique approach to anesthesia induction with TKX injectable and maintenance on isoflurane.

Wind-tunnel experiments on cross-ventilative cooling in a generic isolated building with one heated wall: Impact of opening size

This paper presents wind-tunnel experiments of cross-ventilative cooling in a generic isolated building with an interior heated side wall. Two different sizes of openings are considered: large and small openings. Particle image velocimetry (PIV) is used to determine velocities in the vertical centerplane. Air temperatures in the vertical centerplane are measured using negative temperature coefficient (NTC) sensors. Surface temperatures on the heated wall are measured using an infrared camera. Surface heat fluxes are obtained using heat flux sensors. In both cases the indoor airflow is dominated by the jet through the openings, with higher velocities in the building with large openings. The air temperatures measured with small openings are up to 7.5 % larger than those with large openings. The surface heat fluxes are up to 20 % higher in the building with large openings. The interior convective heat transfer coefficients vary considerably across the heated wall for both opening sizes and can be very different (up to 5 times higher) from those obtained by existing internal convective heat transfer coefficient correlations. The measurement results give insight into the complexity of ventilative cooling and can be used to validate computational fluid dynamics (CFD) simulations of cross-ventilative cooling.

Failure evolution and mechanism of ground collapse due to exfiltration of shallowly buried water pipeline

Exfiltration of defective water pipelines is one of the leading causes contributing to the frequent ground collapses in congested urban areas; hence, revealing the failure evolution and mechanism of this hazard is essential to its prevention and mitigation. In this study, comprehensive experimental model tests were conducted first to characterize the evolution of soil erosion and ground collapse due to exfiltration of shallowly buried defective water pipes and examine the effects of six critical parameters, i.e., opening size and location, pipe pressure and buried depth, groundwater level, and exfiltration condition. Three failure behaviors of strata around leaking waterpipe were identified, i.e., minor disturbance (slight), formation and collapse of an erosion cavity (moderate), and soil fluidization (severe). Moreover, the ground loosening zone induced by cavity collapse could be roughly estimated using the modified flow ellipsoid theory; soil fluidization would occur once the ratio of water pressure head inside the pipe to its buried depth was greater than 2. Subsequently, a validated computational-fluid-dynamics and discrete-element-method (CFD–DEM) coupling method was employed to explore the microscopic mechanism of cavity erosion under the exfiltration flow. It was disclosed that the formation and expansion of a temporary cavity resulted from internal soil erosion, including the emigration of massive fine particles and aggregation of coarse particles around the defective pipe. Finally, the numerical simulation results indicated that cavity erosion would be exacerbated by increasing flow velocity and particle size-ratio, reducing soil fines content, and changing the opening from the pipe crown to its invert.