Opening In Wall Research Articles

An Experimental and Modeling Study on the Effect of Wall Opening Location on the Under-Ventilated Compartment Fire

An experimental and modeling study was carried out to investigate the effect of wall opening location on the mass flow rates of gases through the opening and the associated fire phenomena, such as compartment temperature, projected flame height through the opening, and the heat release rates inside and outside the compartment. A 0.3 m by 0.3 m opening was placed at three different elevations—bottom, middle, and top—of a narrow end wall of a 0.8 m by 1.2 m by 0.8 m (H) compartment. A propane gas burner was used to provide four different fire sizes in the compartment: 90, 110, 130, and 150 kW. The existing correlations for mass flow rates and heat release rates generally do not include the wall opening location as a variable and are functions of only the opening area and height. Based on the experimental and modeling analysis, it is found that the wall opening location affects the internal and external fire phenomena. Two fundamental factors, K and O, are introduced to explain the effect quantitatively. Factor K is the ratio of the air inflow predicted by Fire Dynamics Simulator (FDS) to the existing correlation (0.5AoHo), and Factor O is the ratio of the oxygen consumption rate in the compartment to the oxygen flow rate into the compartment, indicating combustion efficiency. Factor K ranges from 0.78 to 0.94, and O ranges from 0.67 to 0.85 for different opening locations, which suggests that the existing correlations may overestimate the amount of airflow to and the combustion efficiency within the compartment.

165 Environmental Concerns Identified Through an Anonymous Online Survey

Abstract Equine farms, typically, build either stables or barns for the horses to live in and additional facilities to train and work horses (Kidd, Winchell, & Burwash, 1997). Often these training facilities also include indoor riding arenas to ensure continuums in training programs. As the equine industry contributes a total of $122 billion dollars a year to the United States’ economy, it is important to research the farms and facilities that are built and used (American Horse Council Foundation, 2018). 71% of the 335 respondents of an anonymous online survey conducted in the summer of 2018 reported having environmental concerns in the indoor arenas they rode and trained in. The main environmental concerns were dust, moisture, and air movement, though light and temperature were also noted concerns. Analysis was conducted to examine the association of the environmental concerns with different aspect of the indoor arenas such as footing types, attachment to barn, presence of windows and wall openings, and temperature control mechanisms in the facility. A notable trend towards significance is the concern with air movement decreased with the presence of fans and temperature control mechanisms (p< 0.10), while significant associations between lighting concerns were impacted by the presence or absence of translucent panels (p< 0.05) and the number of lights in the indoor arena also impacted whether lighting was a concern (p< 0.05). Overall, dust was always a concern no matter the circumstances. As environmental concerns were expressed by the majority of respondents, it’s important to identify potential reasons for the issues and then work to mitigate the concerns. This involves more targeted research in the future, assessment of mitigation tactics, and resources to design and build indoor arenas and facilities in ways that minimize environmental issues.

Influence of Masonry Infill Wall Position and Openings in the Seismic Response of Reinforced Concrete Frames

It is now widely recognized that the masonry infill frame used in reinforced concrete structures (RC) greatly enhances both the rigidity and strength of the surrounding frame. The lateral loading behavior of this RC frame is different from the frame without infill, although the structural contribution of infill walls is discarded in many countries, including Algeria. This paper aims to focus on the effect of openings and the effect of changing the distribution of masonry panels on the global behavior of buildings. For this, a pushover analysis is carried out to evaluate the seismic performance and assess the behavior of infilled RC, and to study the results related to capacity curve, inter-story drift and energy. The results obtained show that the effect of the openings and changing of the distribution of masonry panels can drastically change the overall behavior of the structures regarding enhancing strength capacities and energy absorption. Noticeable remarks in terms of distributing masonry panels within a frame are observed and several recommendations concerning the present practice might be important to be considered.

Numerical study on the influence of in-plane damage on the out-of-plane seismic performance of masonry infill walls with opening in reinforced concrete frames

The reinforced concrete (RC) frames with masonry infill walls are always subject to in-plane (IP) and out-of-plane (OOP) interaction under earthquakes, and IP damage will affect OOP seismic performance. In order to study IP and OOP interaction of the masonry infill walls with opening in RC frames, we establish a finite element model of RC frame with solid and opening infill walls based on existing tests. We simulated the influence of opening rate and opening aspect ratio on IP and OOP interaction of RC frames with masonry infill walls. The results show that IP damage significantly reduces the OOP stiffness of the RC frames with masonry infill walls; The IP storey drift between 0.5%–2%, the OOP stiffness is reduced by 58.3%–73.7%; Under the same IP damage, the OOP bearing capacity and stiffness of RC frames with masonry infill wall in a larger opening rate has greater degradation level and faster degradation rate; For a given opening rate, the opening with an aspect ratio that closer of infill wall has the least influence on the IP and OOP interaction. Finally, based on the simulation results, a two-parameter exponential equation is found to describe the relationship between the OOP bearing capacity reduction, IP storey drift and the wall opening rate.

Cyclic performance of steel frame fabricated with cold-formed steel composite wall structure

In this study, a novel hybrid wall structure of a hot-rolled steel frame fabricated with a cold-formed steel (CFS) composite wall is proposed. Ceramsite concrete is lightweight concrete that is used in CFS composite walls. The seismic performances, including the failure mode, hysteretic behavior, shear capacity, stiffness, ductility, and energy dissipation performance, of four specimens of steel frame fabricated with CFS composite wall and one specimen of conventional CFS composite wall were evaluated under low-cyclic loading. The experimental results showed that the collaborative working performance of the steel frame and infilled CFS composite wall was optimum, and the proposed fabricated wall structure had a significant effect on the bearing capacity, stiffness, and energy dissipation capacity. The infilled CFS composite walls were damaged earlier than the steel frames. The damage was primarily characterized by the compressive failure at the corners of fillers, loss of diaphragm effect, screw connection failure, and bond-slip failure between the CFS framing and fillers. However, the steel frames exhibited no obvious damage, which effectively restrained the infilled CFS composite walls and prevented them from severe collapse. In addition, enhancing the strength of the fillers and increasing the section area of the studs improved the bearing capacity of the structure; however, they were detrimental to the ductility. Wall opening reduced the bearing capacity and initial stiffness of the structure; however, it improved the ductility. Furthermore, a superposition method was used to calculate the bearing capacity of the proposed structure. The calculated results showed a superior accuracy in comparison with the experimental results.

The effect of venting structures on overpressure caused by an indoor explosion

Introduction. The article considers an accidental indoor gas explosion on condition of pressure relief through openings in which venting structures were installed.A solution to this problem can protect residential buildings from consequences of explosions due to the fact that the volume of premises in residential buildings is small compared to industrial buildings, and it determines more stringent pressure relief conditions at the initial moment of the explosion development. The article shows that pressure can reach critical values in a small space during the motion of a venting structure in the opening before the onset of pressure relief.Goals. The authors aim to identify the pattern of blast load development from the moment of explosion to the attainment of the maximum pressure value with account taken of the properties of venting structures and patterns of their opening. This goal is relevant due to the fact that until now at this stage pressure development has been considered without any account taken of how deeply the venting structure is installed in the wall opening. Much attention was focused on the selection of the opening size.Methods. The methods of the theory of dimensions, numerical and analytical modeling of explosion processes, patterns of gas escape and rigid body motion were applied to obtain dimensionless groups describing the development of an explosive load until maximum values. These dimensionless groups allow identifying explosive loads for rooms having different volumes, which is also a new result.Results. In this work, the influence of individual factors on the ultimate result has been identified. These factors are the room volume, the pressure at which the venting structure starts moving, the mass and position of the venting structure in the opening, the opening perimeter and the rate of explosive combustion.Conclusions. The results, obtained in the course of this work, allow identifying the dynamic load of an explosion at the stage of its growth. This value can be used to set more reliable bearing characteristics of structures for cases of accidental explosions in living accommodations.

A novel Geno-fuzzy based model for hydrodynamic efficiency prediction of a land-fixed oscillating water column for various front wall openings, power take-off dampings and incident wave steepnesses

Accurate efficiency estimation of a wave energy converter (WEC) is a key concept in the design stage. Oscillating water column (OWC) is a promising type of WEC due to its advantages such as proved concept, operational simplicity, accessibility, reliability etc. In this study, for accurate efficiency estimation of an OWC, a novel Geno-fuzzy based model (GENOFIS) was developed, firstly, by improving Adaptive Neuro-Fuzzy inference system (ANFIS) and secondly, incorporating the Genetic algorithms (GAs). Data for training and testing phases of the models were obtained from an extensive wave flume experiments for various OWC underwater opening heights and applied PTO dampings under different incident waves. Both models performed remarkably with a slightly better performance of GENOFIS. The superiority of the GENOFIS model stemmed from that its high performance was attained with substantially low fuzzy rules (only three) where ANFIS required incomparably large fuzzy rules (twenty-seven) and yet achieved a slightly lower performance. Accordingly, very few numbers of fuzzy rules enable the construction of GENOFIS model structure with low complexity, which, in turn, immensely reduce the computational time required. Developed less complicated GENOFIS model is parsimonious, unlikely to suffer from overfitting and has high interpretability and practicality.

A Rare Case of Contained Chronic Rupture of Abdominal Aortic Aneurysm Associated With Vertebral Erosion: Pre- and Post-operative Findings on Computed Tomography and a Narrative Review.

Contained chronic rupture of aortic aneurysm (CCR-AA) is a rare condition that can be associated with vertebral body erosion (VBE) and is often a diagnostic challenge; in fact, CCR-AAs are in general hemodynamically stable and the patients tend to present with a non-specific low-back pain syndrome secondary to vertebral involvement. Furthermore, the differential diagnosis of a retroperitoneal mass can be difficult on medical imaging. We discuss the case of a 79-years-old man, heavy smoker without history of cardiovascular diseases, admitted to the emergency department with signs of left lower limb ischemia. The patient was hemodynamically stable and the medical examination revealed a pulsatile abdominal mass. Doppler ultrasound showed the presence of aneurysmal dilatation of infra-renal abdominal aorta and chronic femoropopliteal occlusion on the left side. The subsequent computed tomography angiography (CTA) demonstrated a voluminous retroperitoneal mass continuous with the infra-renal aorta, which infiltrated the psoas muscles and caused vertebral bodies erosion of the anterior wall in L2, L3 and L4 suspected for CCR-AA or mycotic aortic aneurysm. Furthermore, the examination confirmed the occlusion of the peripheral arterial circulation of the left lower limb. The patient underwent a successful open replacement of the infra-renal abdominal aorta through aorto-aortic prosthetic graft insertion; the visualization during the surgical procedure of a posterior vessel wall opening in continuity with the eroded vertebral bodies associated with negative microbiological culture of the thrombotic material sample, led to the definitive diagnosis of CCR-AA. The post-operative CTA showed successful open vascular treatment. A bypass surgery of the left lower limb was then performed with positioning saphenous graft between femoral common artery and posterior tibial artery. The patient was finally discharged in good clinical conditions.

Permeability and wind induced internal pressures in steel sheds

The wind induced internal pressure in a typical, porous steel-clad shed is dependent on the distribution of external pressures and the permeability across the envelope. The permeability of the envelope is dependent on the construction methods and wall fixtures (i.e. windows, roller doors etc). The permeability of walls range between 0.5% and 1.5%, with the surfaces that have roller doors having more leakage.Internal pressure fluctuations in these porous buildings are generally much lower than the external pressure fluctuations. The magnitude of the internal pressure is significantly influenced by the actual distribution of permeability and the magnitude of the external pressures on the windward and leeward surfaces.Positive internal pressures are generated in cases where the ratio of the windward/leeward wall opening ratio exceeds 0.5, in contradiction to recommended negative pressures given in AS/NZS 1170.2:2021. This is mainly due to the higher magnitude of positive external windward wall pressure compared to the external suction pressures on the other walls. Such a scenario could be the governing design criterion for the cladding and the structural system of these types of buildings.

Analysis of different ventilation strategies and CO2 distribution in a naturally ventilated classroom

CO2 monitoring has proven to be an effective and affordable way of controlling air ventilation rates, a paramount task for minimizing airborne contagions in indoor shared spaces. In this work, the CO2 distribution in a naturally-ventilated classroom has been thoroughly characterized, gaining information not only on the effectiveness of diverse ventilation strategies but also on the expected differences between CO2 values when varying the sampling location within the room. The results confirm that an adequate renewal of the air in the room requires the use of cross-ventilation, with openings in different walls. Furthermore, it was found that ventilation is optimized, for a given total opening area, when the openings are distributed as much as possible among different windows. For most of the studied conditions, a global windows opening area of 1.24 m2 with an open door was typically enough to yield CO2 concentrations below 700 ppm. The CO2 readings displayed a noticeable and consistent dependency on the sampling height, with below-average values at 0.75 m, the highest concentrations at 1.5 m, and levels close to the average when sampling at a height of 2.2 m. For a given height, the influence of the sampling location within the room was weaker, and more dependent on the specific ventilation strategy applied. However, the tests consistently showed CO2 records significantly lower for sensors installed on the walls. Besides a detailed spatial and temporal characterization of the ventilation process under different ventilation strategies, these results are thought to provide useful and novel information for a judicious placement of CO2 monitoring systems.

Effect of Wind Loads on Low-Rise Pitched and Circular Arch Roof Structures: A Comparative Study based on Numerical Simulation

Through numerical simulations based on Computational Fluid Dynamics (CFD), this study examines the effect of wind load operating on a pitched roof and a circular arch roof of an identical plan area of a storage structure with one wall opening. Many numerical simulations have been performed by other researchers for other types of roofs to understand the behavior of wind flow associated with them. Also, the wind standards of multiple countries have provided the Coefficients of Pressures for standard building shapes. However, there is lack of similar work for structures having one wall opening. Ansys CFX fluid flow software has been used to carry out the simulations using a standard k-ε turbulence model. The simulations have been carried out for 7 wind incidence angles at an interval of 30ᵒ. Pressure, Force, Moment, Drag and Lift Coefficients generated on the roofs were compared. It was found that, although variation in these coefficients w.r.t the wind incidence angles are similar for both the roofs types, the sharp-edged rooftop of the pitched roof contributes to higher magnitudes of these coefficients as compared to the smooth arch roof. Mathematical modules between the face average of pressure coefficients and the wind incidence angles were established in a polynomial form which could be used to find the face average of pressure coefficients and corresponding pressures and forces for arbitrary wind incidence angles.

A New Methodology Based on Cell-Wall Hole Analysis for the Structure-Acoustic Absorption Correlation on Polyurethane Foams.

Polyurethane foams with a hybrid structure between closed cell and open cell were fabricated and fully characterized. Sound absorption measurements were carried out in order to assess their acoustic performance at different frequency ranges. The cellular structure of these systems was studied in detail by defining some novel structural parameters that characterize the cell wall openings such as the average surface of holes (Sh), the number of holes (h), and the area percentage thereof (%HCW). Therefore, these parameters allow to analyze quantitatively the effect of different structural factors on the acoustic absorption performance. It has been found that the parameters under study have a remarkable influence on the normalized acoustic absorption coefficient at different frequency ranges. In particular, it has been demonstrated that increasing the surface of the holes and the percentage of holes in the cell walls allows increasing the acoustic absorption of these types of foams, a promising statement for developing highly efficient acoustic insulators. Additionally, we could determine that a suitable minimum value of hole surface to reach the highest sound dissipation for these samples exists.

Review on a cesarean section in the cow: Its incision approaches, relative advantage, and disadvantages.

Dystocia is an abnormal and difficult birth in which the first or the second stage of labour is markedly prolonged and subsequently found impossible for the dam to deliver without artificial aid. In cattle, it can be relieved by different obstetric methods, including the cesarean operation and fetotomy. Caesarean section is the extraction of the fetus or foeti from the dam, through a surgical opening in the abdominal wall and the uterus. This surgical method can be performed by about eight alternative surgical approaches in bovines with its advantages and disadvantages. However, the selection is dependent on many factors like the type of dystocia, the cows and environmental conditions, the availability of assistants, and the surgeon's preference. For cows, most surgeons use a standing left paralumbar celiotomy. However, the left oblique approach is also preferable under most circumstances because the uterus is readily exteriorized, limiting peritoneal cavity contamination. Besides, alternative approaches are also available that will further limit the potential for contamination but many junior surgeons perform the left paralumbar celiotomy using the same approach each time due to their comfort with one specific approach or lack of familiarity with other available options. Therefore, the objective of this review is to provide basic insights and highlight the cesarean section incision approaches with their relative advantages and disadvantages in cows.

Percutaneous Tracheostomy: A Bedside Procedure.

Percutaneous tracheostomy is a bedside surgical procedure that creates an opening in the anterior tracheal wall. Tracheostomy is performed in patients expected to require mechanical ventilation for longer than seven to 10 days. This bedside percutaneous tracheostomy has been used since the late 1990s. Tracheotomy tubes are of various kinds like cuffed vs. uncuffed, fenestrated vs. unfenestrated, single lumen vs. double lumen, and metal vs. plastic. Its indications are categorized into emergency vs. elective. The most common emergency indication is acute airway obstruction, and the elective indication is prolonged intubation. There is no absolute contraindication, but a physician should consider severe hypoxia requiring high oxygen and coagulopathy. Percutaneous tracheostomy is a new technique requiring different skills. Advantages of percutaneous tracheostomy are as follows - it is performed at the bedside, procedural time is less, the cost is less, does not need operating schedule time. Percutaneous tracheostomy is generally performed by otolaryngologists, general surgeons, interventional pulmonologists, thoracic surgeons, or intensivists.

How to cope with downstream groundwater deterioration induced by cutoff walls in coastal aquifers

Cutoff walls have been widely used to control seawater intrusion (SWI) in coastal regions. However, previous research mainly focused on the protective effect of cutoff wall on the upstream groundwater system, the downstream groundwater deterioration of coastal aquifers (between the cutoff wall and sea) induced by the installation of cutoff walls was not clarified yet. We implemented indoor experiments and numerical simulations to investigate the downstream saltwater behaviors considering the construction of cutoff walls. The results revealed that cutoff walls could enable the rise of downstream saltwater wedge, widen the mixing zone width, mitigate the freshwater discharge, and aggravate the seaside groundwater deterioration in coastal aquifers. We further found that the wall opening size, wall distance to the sea, hydraulic gradient, and dispersivity could alter both the downstream spatial salt distribution and freshwater discharge, while hydraulic conductivity only affected freshwater discharge. It needs to be noticed that seawater invades the inland aquifer dramatically when the hydraulic gradient is less than 0.004 in our cases. Therefore, cutoff walls are not suitable for coastal aquifers with low hydraulic gradient. With the decrease of the distance between the wall and the sea boundary, the cutoff wall remains effective for the SWI control. Thus, we found that a cutoff wall closer to the sea can somehow minimize the groundwater salinization of coastal aquifers without increasing the construction cost. These results reveal the adverse side effects of the cutoff wall in downstream aquifer and further suggest additional countermeasures.

The Effect of Shear Wall Openings on the Response Reduction Factor

This research attempts to investigate the effect of shear wall openings on the response reduction factor. Openings are commonly necessary because of other engineering disciplines’ requirements. When openings are modest in proportion to the size of the wall, their effects are frequently disregarded. On the other hand, when these openings are large or located in a high-risk area, they can have a significant impact. A broad literature review has been conducted in the present study. A verified comparative example consisting of eight stories was studied. Then, a numerical study has been conducted on two different model sets with 16 and 8 stories, which were designed according to the Egyptian code of loads, ECP-201 (2012), and checked according to the Euro code, EC8 (2004). ETABS software was used to conduct pushover analysis before and after applying different-sized openings. The ground-opening effect has also been studied. The results show that by increasing the opening area, the R-factor was reduced. It is more influenced by the opening height than the width, though. By increasing the number of stories, the reduction percentage in the R-Factor increased for openings that are less than 30% of the wall area. The R-factor increases slightly when half of the reinforcement bars are added. Doi: 10.28991/CEJ-2022-08-04-013 Full Text: PDF

The Inflammatory Cytokine Imbalance for Miscarriage, Pregnancy Loss and COVID-19 Pneumonia.

Pregnancy can be defined a vascular event upon endocrine control. In the human hemo-chorial placentation the chorionic villi penetrate the wall of the uterine spiral arteries, to provide increasing amounts of nutrients and oxygen for optimal fetal growth. In any physiological pregnancy the natural maternal response is of a Th1 inflammatory type, aimed at avoiding blood loss through the arteriolar wall openings. The control of the vascular function, during gestation as in any other condition, is achieved through the action of two main types of prostanoids: prostaglandin E2 and thromboxane on the one hand (for vasoconstriction and coagulation), prostacyclin on the other (for vasodilation and blood fluidification). The control of the maternal immune response is upon the responsibility of the fetus itself. Indeed, the chorionic villi are able to counteract the natural maternal response, thus changing the inflammatory Th1 type into the anti-inflammatory Th2. Clinical and experimental research in the past half century address to inflammation as the leading cause of abortion, pregnancy loss, premature delivery and related pulmonary, cerebral, intestinal fetal syndromes. Increased level of Interleukin 6, Interleukin 1-beta, Tumor Necrosis Factor-alfa, Interferon-gamma, are some among the well-known markers of gestational inflammation. On the other side, COVID-19 pneumonia is a result of extensive inflammation induced by viral replication within the cells of the respiratory tract. As it may happen in the uterine arteries in the absence of an effective fetal control, viral pneumonia triggers pulmonary vascular coagulation. The cytokines involved in the process are the same as those in gestational inflammation. As the fetus breathes throughout the placenta, fetal death from placental thrombosis is similar to adult death from pulmonary thrombosis. Preventing and counteracting inflammation is mandatory in both conditions. The most relevant literature dealing with the above-mentioned concepts is reviewed in the present article.

Analysis of the scatter in fatigue life testing of thick thermal cut plate edges

ABSTRACT Structural elements of ships are subjected to a high number of cyclic loads, which are critical to fatigue life. Especially for ultra-large container ships the cutting of thick steel plates with high finishing quality and good fatigue life is important, e.g. located at openings in walls and decks of ships. This study presents a series of fatigue tests with 50 mm thick S355 specimens that are thermally gas cut on different shipyards. The obtained stress-life (S-N) curve contains significant horizontal scatter which often occurs for specimens that spend a high number of cycles on crack initiation. However, it is found that both the local stress concentrations and the origin of failure affect the number of load cycles significantly. Accounting for local stress concentrations provides an explanation for the initially encountered scatter in the S-N curves and indicates possible limitations of the nominal stress approach for thermal cut edges.

Virtual simulation of the biomechanics of the abdominal wall with different stoma locations

An ostomy is a surgical procedure by which an artificial opening in the abdominal wall, known as a stoma, is created. We assess the effects of stoma location on the abdominal wall mechanics. We perform three-dimensional finite element simulations on an anatomy model which was generated on the basis of medical images. Our simulation methodology is entirely based on open source software. We consider seventeen different locations for the stoma incision (trephine) and we simulate the mechanical response of the abdominal wall when an intraabdominal pressure as high as 20 kPa is applied. We focus on factors related to the risk of parastomal hernia development such as the deformation experienced by the abdominal wall, the stress levels supported by its tissues and the corresponding level of trephine enlargement. No significant dependence was found between stoma location and the levels of abdominal wall deformations or stress supported by tissues, except for the case with a stoma located on the linea alba. Trephine perimeter and area respectively increased by as much as 44% and 85%. The level of trephine deformation depends on stoma location with considerably higher trephine enlargements found in stomas laterally located with respect to the rectus abdominis muscle.

Seismic behavior of full-scale wall piers with high-strength steel reinforcement

The introduction of openings in structural walls could cause unfavourable seismic behaviour, leading to stringent reinforcement requirements for wall piers. High-strength steel with a reduced amount of reinforcement has the potential to relieve reinforcement congestion. However, the effect of the reduced areas of high-strength steel on the seismic performance of wall piers remains largely unknown, impeding its application in earthquake-prone areas. Through experimental investigation, this research aimed to reveal the benefits and limitations of using high-strength steel in wall piers. Four full-scale wall pier specimens with a height-to-length aspect ratio of 2.8 were subjected to lateral loading and a constant axial load. The parameters that varied in the specimens included concrete strength, steel reinforcement yield strength, and loading type. Test results showed that the 50% reduction in the amount of high-strength steel reinforcement had minor influence on the failure mode and lateral load-resisting capability. However, it had implications for the flexure-shear interaction and ultimate load-resisting mechanism of wall piers. All tested wall piers experienced spalling and crushing along the diagonal strut although their peak average stress was less than the shear stress limit associated with the crushing of concrete struts, as recommended in ACI 318–19. The effective stiffness estimates per the existing code provisions were found to be consistently higher than the one measured for the tested wall piers.