Floor Structure Research Articles

Transperineal Three-Dimensional Ultrasound Combined with Real-Time Shear Wave Elastography Imaging to Assess Changes in Pelvic Floor Structure During Pregnancy and Delivery

Transperineal Three-Dimensional Ultrasound Combined with Real-Time Shear Wave Elastography Imaging to Assess Changes in Pelvic Floor Structure During Pregnancy and Delivery

Consideration of the conversion factor from air dose rates to individual external dose per hour after the Fukushima accident—individual external dose measurements of a TEPCO employee in Fukushima prefecture over a 9 year period—

The accident at Fukushima Daiichi Nuclear Power Plant (FDNPP) in 2011 resulted in the dispersion of radioactive materials throughout the surrounding area and an increase in the air dose rate was even confirmed in Fukushima City, which is located approximately 60 km northeast of FDNPP. A Tokyo Electric Power Company (TEPCO) Holdings employee, who has lived and worked in Fukushima City since the FDNPP accident, measured individual external doses, GPS data, and his activities in Fukushima Prefecture over a 9 year period beginning in 2014. This data provides valuable information about the area. The data show the following results. (i) Comparison of the air dose rate at the home location to the individual external dose per hour at the home shows that the average conversion factor has increased over the 9 years and exceeded 0.3 since 2019, indicating an overall relatively good correlation. (ii) Individual external doses measured in the office on the fourth floor of a concrete structure in Fukushima City have not changed significantly from 2014 to 2022, when air dose rates showed a decrease. (iii) Outdoor individual external doses, such as those measured when commuting on foot, have a relatively strong correlation with air dose rates from airborne monitoring with the conversion factor of about 0.6. The conversion factor do not differ significantly from 2014 to 2022.In this study, the individual external dose data is applicable to the TEPCO measurer and is not necessarily representative of all residents of Fukushima City. However individual external dose data for 9 consecutive years will be useful for estimating individual external doses from air dose rates, and estimating annual additional exposure doses, if even some of them are applicable to similar life patterns and lifestyles.

Design and Implementation of a MIMO Integral Resonant Control for Active Vibration Control of Pedestrian Structures

In contemporary construction, the prevalence of vibration serviceability issues in lightweight and slender structures has become increasingly common, owing to advancements in building materials and construction methods. While these structures often meet the criteria for ultimate limit states, they can still elicit complaints due to excessive vibrations induced by human activity. To address this challenge, the integral resonant control (IRC) technique has emerged as a favored approach for actively damping vibrations in various systems. This study introduces a fresh perspective by proposing the implementation of a multi-input multi-output (MIMO) IRC scheme for active vibration control (AVC) specifically tailored for pedestrian structures utilizing inertial mass actuators. This application of MIMO IRC for AVC represents a novel advancement in the field, offering a new solution to address vibration issues in lightweight and slender structures. Building upon a common framework and design methodology outlined in previous research, this work presents a novel application of MIMO IRC for AVC. The designed controller undergoes rigorous testing and is implemented on a laboratory floor structure to validate its efficacy. The outcomes of this study demonstrate the effectiveness of the proposed MIMO IRC scheme in actively damping vibrations, thereby enhancing the serviceability and comfort levels of lightweight and slender structures subjected to human-induced excitations.

Automatic anal sphincter integrity detection from ultrasound images via convolutional neural networks.

The anal sphincter complex comprises the anal sphincter and the U-shaped deep and superficial puborectalis muscle. As an important supporting structure of the posterior pelvic floor, together with its surrounding tissues and muscles, the anal sphincter complex maintains the normal physiological functions of defecation and continence. The plane required for diagnosing anal sphincter injury and the diagnosis of anal sphincter integrity through pelvic floor ultrasound are highly dependent on sonographers' experience. We developed a deep learning (DL) tool for the automatic diagnosis of anal sphincter integrity via pelvic floor ultrasound. A 2D detection network was trained to detect the bounding box of the anal sphincter. The pelvic floor ultrasound image and its corresponding oval mask were input into a 2D classification network to determine the integrity of the anal sphincter. The average precision (AP) and intersection over union (IoU) were used to evaluate the performance of anal sphincter detection. Receiver operating characteristic (ROC) analysis was used to evaluate the performance of the classification model. The Pearson correlation coefficients (r values) of the topmost and bottommost layers detected by the CNN and sonographers were 0.932 and 0.978, respectively. The best DL model yielded the highest area under the curve (AUC) of 0.808 (95% CI: 0.698-0.921) in the test cohort. The results from the CNN agreed well with the diagnostic results of experienced sonographers. We proposed, for the first time, a CNN to obtain the plane required for diagnosing anal sphincter injury on the basis of pelvic floor ultrasound and for preliminarily diagnosing anal sphincter injury.

Assessment of the seismic failure of reinforced concrete structures considering the directional effects of ground motions

Seismic intensity measures at different levels significantly impact the seismic damage of building clusters. Reinforced concrete (RC) structures are a type of building widely used in different regions worldwide. A large amount of field seismic damage observation data indicates that within the same seismic intensity zone, the directional effects of varying ground motions lead to significant differences in damage to RC structures on different floors. However, relatively little research has been conducted on estimating the seismic fragility and vulnerability of RC structures considering the directional effects of seismic action. To further study the directional effect of seismic motion on the damage of different floors, this study conducted dynamic time history and spectral analyses on 1472,379 acceleration records in multiple directions obtained from monitoring at nine actual seismic stations during the 2008 Wenchuan earthquake in China. This paper innovatively reports on the actual damage features of RC structures during the Mw6.2 magnitude Jishishan earthquake in Gansu Province, China, on December 18, 2023 (the most severe destructive earthquake in China in 2023) and analyses the influence of earthquake directionality on the damage to different floors of RC structures. A three-dimensional numerical model of a four-story RC frame structure was established using numerical simulation and the finite element method. Different intensity measures were taken to input seismic excitations of different intensities into the RC structure in the 0°, 30°, 60°, and 90° directions, and damage simulation analysis was conducted. The nonlinear dynamic time history curves of structures under multiple directions of seismic excitation in different intensity zones have been developed. Using the interstory stiffness and interstory displacement angle as engineering demand parameters, damage assessment curves and stress clouds for RC structures with 1–4 floors considering different seismic directional effects were generated. The analysis results and major findings indicate that the seismic sequence in the 0° direction has a relatively heavy impact on the first floor of the RC structure in zone IX, which is consistent with the actual field observation results.

Controlling Seepage Flow Beneath Hydraulic Structures: Effects of Floor Openings and Sheet Pile Wall Cracks

Using one opening (filter) within the floors of hydraulic structures is a known technique to relieve the seepage effects on their floors. In this study, a new method to control seepage flow by using two identical filters instead of one was tackled numerically. A comparative analysis of using one versus two filters was conducted for different thicknesses of the permeable stratum, apron size (b), filter length, and sheet pile wall depths. Results indicate that two filters are considerably more effective than using one where the overall uplift force, the maximum potential head, and the hydraulic exit gradient downstream of the floor are reduced to 42–56%, 42–51%, and 66–76%, respectively, compared to one filter, while slightly increasing seepage flow by 1–7%. Many reasons can lead to horizontal openings (cracks) appearing along the sheet pile walls beneath hydraulic structures. The current study tackled their effects on seepage flow for the first time and examined their impact on the floor. A crack in the upstream sheet pile wall can increase total uplift forces by up to 40%, while a crack in the downstream sheet pile wall can increase the hydraulic exit gradient by up to 230%

Laboratory measurement of treadmill noise under several speeds, runners, and floor coverings

Treadmills are an important generator of noise in the retail fitness and multi-family housing environments. Field studies have demonstrated that treadmills have a low-frequency sound characteristic, and treadmill use can lead to neighboring-occupant annoyance and necessitate consideration in building design and space planning. This work presents sound level measurements of a treadmill in operation to report sound levels and the effect of runner speed, runner cadence, and floor covering. Tests were conducted on an elevated 6-inch concrete slab in a vertical laboratory setting, and results are in terms of measured SPL in the lower room. Runner speed and floor covering were confirmed to be relevant variables in sound levels due to treadmill noise. Spectral shapes in multiple tests were found to be similar despite presence and composition of floor covering. Results on the effect of runner cadence are not conclusive. SPL was lower than expected due to the relatively stiff structural floor, and future testing should continue to pursue higher source levels.

Complex Heat Exchange of Structures Taking Into Account Radiation Cooling in Indoor Ice Rinks

Statement of the problem. The aim of the work is to construct a numerical model of complex radiation-convective heat exchange of the roof structures of an indoor skating rink with moist air of the upper zone to identify the dependencies of the increase in the velocity and area of condensation of water vapor on the height of the room Results. Based on the results of a numerical study of the process of complex non—stationary heat exchange of the system «surface of the floor structure — indoor air –– ice surface», theoretical dependences of the increase in the velocity and area of condensation of water vapor from the vertical coordinate under the action of radiation cooling from the ice field were obtained for the first time. Conclusions. The obtained dependences allow us to theoretically justify the choice of rational technical solutions and operating modes of ventilation and air conditioning systems in the upper zone to prevent condensation on the internal surfaces of building and enclosing structures.

High-speed multi-camera videogrammetric measurement of full-field 3D motion and deformation in full-scale crash testing of typical civil aircraft

Crashworthiness has been and will continue to be the main concern in aircraft design. Crash tests are essential approaches to investigate the crashworthiness of civil aircraft. Videogrammetric methods have been employed in crash tests to overcome the disadvantages of laborious, time-consuming measurement data collection using contact sensors. However, previous methods using a single pair of cameras still face challenges in large-scale applications due to the inherent contradiction between measurement range and accuracy. In this paper, a videogrammetric method using four high-speed cameras is proposed to measure the full-field three-dimensional (3D) dynamic deformation for evaluating the impact response characteristics of the full-scale crash test aircraft. Increasing the number of high-speed cameras not only can enhance the resolution and then measurement accuracy of object, but also expands the measurement range significantly. To ensure the performance of digital image correlation (DIC) used for large-scale measurement range, a speckle pattern optimization design and fabrication method is presented to generate the random speckle with uniform spraying size and density. A global calibration method based on the high-precision total station is proposed to unify the data of different stereovision subsystems. The implementation of the proposed method is illustrated through a 6.0 m/s full-scale crash test using a civil aircraft approximately 24 m in length. The impact velocity, full-field displacement and strain of the fuselage structure are measured. The results show that the test data are complete and reliable. After the vertical crash at 5.71 m/s, the lower structure of the cabin floor is seriously deformed, and the upper structure of the fuselage in the central wing area is obviously deformed due to the inertia effect of the wing. The stiffness difference of the different fuselage segments results in significant differences in dynamic response. The higher the stiffness is, the smaller the deformation. This work may provide some valuable technical insights that could support the crashworthy design, verification, and certification of civil aircraft.

Study on the safe distance of spatial intersecting tunnel cavern under ground shock

The vertical distance of intersection area is an important factor dominating the service performance of spatial intersecting cavern. To obtain the influence of vertical distance on the dynamic response of orthogonal spatial intersecting caverns under ground shock, the plastic region and peak particle velocity (PPV) distribution are investigated by numerical simulation. A finite-dynamic model is established to simulate the mechanical response of the deeply bureid structure subjected to coupled static and dynamic load, with an artifical boundary condition setting method. The results indicate that as the vertical distance decreases, the plastic region in the intersection area gradually merges, while the bolt support at the lower cavern vault effectively suppresses the destruction of the intersection area. The free surface of the lower cavern vault weakens the bottom support conditions of the upper cavern floor structure, resulting in higher PPV when vertical distance is smaller. Conversely, as vertical distance increases, isolation effect of upper cavern on ground shock weakens, leading to an increase and followed by a decrease in PPV at the lower cavern vault and straight wall. Morever, when vertical distance exceeds than 3 times the cavern characteristic size, the lower cavern exhibits dynamic response characteristics of deeply buried single-cavern. when vertical distance within 3 times, there is significant interaction between caverns with inverse relationship between dynamic axial stress on bolts in intersection area and PPV at lower cavern vault. It is recommended to use comprehensive criteria involving PPV and plastic region distribution to evaluate safety performance for spatial intersecting cavern.

Development of a vibration-damping, sound-insulating, and heat-insulating porous sphere foam system and its application in green buildings

With the development of green buildings, people pay more attention to the quality of the indoor sound environment. The air sound insulation performance of floors and exterior walls plays a key role in today's green buildings. The thermal performance of the enclosure structure's floor and exterior wall heat transfer resistance is an important factor in reducing building carbon emissions in green buildings. The aim of this paper is to study the efficiency of the acoustic and thermal insulation of a foaming system with porous carbon balls and the combination of different structural ways of construction boards and external walls. The acoustic and thermal parameters of different sound insulation and thermal insulation systems designed with porous carbon sphere foam and inserted into the floors and exterior walls are compared to highlight the optimal structure. The theoretical and experimental tests showed that to improve the sound insulation performance of the floor, a sound insulation system needs to be placed on the surface of the floor in contact with the impact object and inlaid in the vertical gap in contact with the floor and the wall. Furthermore, it has been determined that the surface of the foam particle acoustic ball with micropores has good sound absorption performance. Finally, the high-quality building thermal insulation material with low thermal conductivity in any combination with the floor slabs and the external wall structure improves the thermal insulation performance.

Lap Length of Steel Bars Between Novel Prefabricated Wall and Foundation Floor Structures: Full-Scale Experiment

In the context of promoting environmentally friendly practices, prefabricated components are increasingly utilized in civil engineering design and construction. Prefabricated shear walls, in particular, have become prevalent in contemporary residential and office buildings. Following an economic analysis of the construction steps for prefabricated walls, Shanghai Hengxu Energy Conservation Company developed a novel type of prefabricated wall for use in building basements. This innovative wall consists of two thin plates joined by distributed tie pieces, with an internal steel bar cage positioned between them. The core concrete is cast in place between the plates. The wall is designed to withstand water and soil pressures from underground and connects to the basement floor through overlapping steel bars. The effectiveness of the wall's integration with the foundation floor depends on the lap length of the steel bars, a critical factor in structural design and construction. To optimize the lap length, three full-scale specimens were tested, differentiated by varying steel bar lap lengths: 0.8 lae, 1.0 lae, and 1.2 lae, where lae represents the basic anchorage length. The specimens were subjected to horizontal loading to assess failure modes, crack propagation, load-displacement behaviors, and stress-strain responses of the reinforcements. The experimental results revealed that increasing the lap length of the steel bars beyond 0.8 lae does not significantly enhance the bearing capacity or deformation potential of the specimens.

A subspace parameter identification method for nonlinear structures under oversampling conditions

In engineering practice, sampling frequencies much higher than the Nyquist frequency are often used to obtain accurate measurements of the dynamic characteristics of nonlinear systems. However, it may lead to oversampling when using the nonlinear subspace identification method (NSIM). This study proposes a subspace parameter identification method to address the identification of nonlinear structures under oversampling conditions. The proposed method first employs the prediction error method (PEM) to estimate the linear part of the state space model. In noisy environments, the PEM can achieve more accurate results than the NSIM by minimizing an error criterion function. The initial values fed into the PEM are obtained by the stochastic subspace identification method. The nonlinear part of the state space model is estimated by solving a linear regression equation. The proposed method effectively reduces the impact of high sampling frequencies on identification accuracy by combining data with different sampling frequencies to construct the linear regression equation. Among them, the low sampling frequency data is obtained by downsampling the high sampling frequency measurement data. The proposed method effectively reduces the effect of high sampling frequencies and environmental noise on identification accuracy by accurately estimating both the linear and nonlinear parts of the state space model. The identification accuracy of the proposed method is numerically verified by a chain-type structure with five degrees of freedom and a cantilever beam structure. Additionally, experimental verification is carried out on a two degrees of freedom floor structure with local nonlinearities. The results show that the proposed method achieves high identification accuracy in oversampling conditions and noisy environments.

A case report of urethral prolapse in young girls: Clinical manifestations and surgical management

Background and importanceUrethral Prolapse (UP), first described by Solinger in 1732, is a rare condition characterized by the circular protrusion of the distal urethral mucosa through the external meatus, forming a hemorrhagic, sensitive vulvar mass. This condition is most commonly observed in prepubertal black females. This case report details the clinical manifestations and surgical management of UP in three young girls. Cases presentationThree girls, aged 4, 5, and 6 years, were admitted with symptoms of vaginal blood spotting. Physical examinations revealed moderate bleeding and a red ring of congested, edematous tissue prolapsing through the urethral meatus. Diagnostic procedures confirmed UP, and surgical management was undertaken. The surgical approach involved the complete excision of the prolapsed tissue and mucosal-to-mucosal anastomosis under general anaesthesia. Postoperative follow-up over a mean period of 11 years showed no recurrence or urethral stricture. Clinical discussionUP is a rare benign condition primarily affecting the female urethra, with several hypothesized etiologies, including weak pelvic floor structures and increased intraabdominal pressure. The typical presentation includes vaginal bleeding and a doughnut-shaped mass around the urethral meatus. Conservative management may be considered for mild cases, but surgical excision is recommended for severe cases, offering a safe and effective solution with low recurrence rates. ConclusionsUP in children, although rare, should be considered in cases of unexplained vaginal bleeding. Diagnosis is primarily clinical, and surgical resection provides a definitive and cost-effective treatment.

SELECTION OF OPTIMAL PARAMETERS OF A LIGHTWEIGHT FLAT FLOOR WITH VOIDS MADE OF PLASTIC BALLS

Formulation of the problem. Architectural and construction design of buildings using reinforced concrete has led to an increase in the number of objects with an individual space-planning structure, a rich variety of facade and volumetric solutions. Today the question of the effectiveness of using flat prefabricated monolithic lightweight floors in the construction of multi-storey buildings with individual space-planning and architectural solutions is relevant. In a market economy interest in the issue of rational use of resources, namely the cost of concrete and reinforcement in construction, has sharply increased, which is directly related to attracting investment. As it is known, when designing buildings from prefabricated monolithic reinforced concrete, in contrast to prefabricated concrete, there is greater freedom in adopting the space-planning parameters of the building, and there may also be simpler design solutions, in particular for floors. The constructive solution of floors depends on numerous requirements for the building as a whole and directly for the floor. One of the requirements that influences the attraction of investments is a small material-intensive floor covering with significant spans of buildings of various structural systems. The effective use of lightweight precast monolithic reinforced concrete floors with voids made of plastic balls in construction requires a comprehensive technical and economic analysis of this innovative solution for the precast monolithic reinforced concrete floor structure. The purpose of the article is to perform a technical and economic comparison of various design options for a flat lightweight prefabricated monolithic floor. The influence of floor parameters on the consumption of concrete and reinforcement is considered. Conclusion. As a result of the research, it was established that it is rational to use hollow balls made from recycled materials as a material for making voids from balls in flat floors. Moreover, all studied floor options with spans of 6 m, 7 m, 8 m and void sizes made of balls with diameters of 180 mm, 315 mm and 50 0mm meet the requirements of the first and second groups of limit states.

Improvement of Shock Noise Insulation by Elastic Gaskets in Floating Floor Structures

Improvement of Shock Noise Insulation by Elastic Gaskets in Floating Floor Structures

Optimizing indoor air quality and energy efficiency in multifamily residences: Advanced passive pipe system parametrics study

AbstractThis research focuses on enhancing natural ventilation in multifamily residential buildings to improve air quality and minimize reliance on mechanical ventilation, thereby reducing energy consumption. The study pioneers the integration of passive pipe systems within structural floor slabs and building envelopes, aiming to overcome the inherent challenges of indoor environmental quality (IEQ) related to design constraints, occupant behavior, and urban context. Our innovative approach, utilizing a novel application of Grasshopper for precise architectural modeling and Ansys for advanced multiphysics simulation, enables a detailed comparative analysis of airflow dynamics across various system configurations. A comprehensive literature review underscores the significance of natural ventilation as a key passive cooling strategy, vital for reducing energy use and enhancing IEQ in the face of urbanization challenges. Our empirical findings reveal that configurations with more inlet and outlet pipes significantly outperform simpler ones, with a notable configuration of 11 pipes (5 × 6) achieving an actual-to-required ventilation rate increase in 158.15%. This evidence highlights the substantial benefits of adopting complex system configurations for improved ventilation efficiency. The study’s outcomes include impactful design recommendations for adopting enhanced natural ventilation strategies in multifamily residential buildings. These recommendations promise to inform sustainable urban planning and building management strategies, offering a scalable solution for cities seeking to balance growth with environmental sustainability. By demonstrating the clear advantages of targeted passive cooling interventions, this research contributes valuable insights toward achieving energy efficiency and superior IEQ in residential buildings, paving the way for future exploration in diverse climatic and urban contexts.

Efficiency of Pile Foundation in the Construction of Basement Floors of Structures on Collapsible Soil

Efficiency of Pile Foundation in the Construction of Basement Floors of Structures on Collapsible Soil

STUDY OF THE STRESS-STRAIN STATE OF A REINFORCED CONCRETE SLAB USING HYDROSTATIC METHOD

The scientific article is devoted to a complex study of the stress-strain state of a monolithic slab, implemented using the author’s method of hydrostatic loading, which involves setting the load by the weight of water and regulating its value by the height of the water column. To implement the given procedure, we used a tank-shaped facility for field tests of structures for vertical short-term and long-term loads. To determine the deflections of the loaded slab system, we installed mechanical deflection gauges of the 6PAO brand under the slab at pre-planned places. The short-term loading of the selected section of the monolithic reinforced concrete slab involved three stages. The first two stages of loading were carried out step by step, with a load step of 1–2 kN/m2 and a time delay until the arrows of the deflection gauges stopped. The maximum load on the slab was 5 kN/m2. The maximum deflection was recorded for point 2 (conventional centre of the tank) and was equal to 1.27 mm. The third stage of slab loading proceeded by analogy with the previous two. The maximum load on the slab was 8 kN/m2. The maximum deflection was recorded for point 2 and equalled 1.57 mm. After completing the stepped loading, the water tank was left on the slab to track vertical deflections for 32 days. The study experimentally established that the displacement of the examined slab in the span and support zones under increased load did not exceed the normative values. We carried out numerical verification using finite-element modelling followed by calculations in a linear and non-linear model. The theoretical and experimental calculation results showed a qualitative and quantitative data match (the difference did not exceed 15–20%). The nature of the change in the deflections remained practically linear and closely correlated with the experimental data (the values of the maximum deflections were equal to 1.16 and 1.57 mm, respectively, which was less than the maximum allowable deflection of 30 mm). Based on the results of the comprehensive study, we have made proposals for further safe operation of the investigated slab system through the use of lightweight floor elements (lighter filling, reduction of screed thickness, and others) to limit the total load on the overlapping to 10 kN/m2 (taking into account dead weight of the slab, load from floor structure and partitions, load from people and various types of construction and other equipment). Keywords: hydrostatic loading, testing, concrete, calculation, deflection, modelling.

Probabilistic assessment of the dynamic response of floors under multi-pedestrian walking loads

The dynamic behavior of floors under multi-pedestrian walking loads affects the safety, serviceability, and comfort of floor occupants. The complexity of pedestrian-induced dynamic loads necessitates a probabilistic approach to understand and predict the performance of floors under such conditions. This paper investigates the dynamic response of floors subjected to multiple-pedestrian walking loads, taking into account the randomness of the walking path and walking load. The research focuses on probabilistic multi-pedestrian walking load scenarios and utilizes Monte Carlo simulations to analyze the modal loading. An analytical equivalent Power Spectral Density (PSD) function for the modal force, based on an existing model introduced for footbridges, is proposed. Furthermore, a formula is developed to estimate the mean value of the peak acceleration response of floors. The findings of this study contribute to the advancement of simplified methods for predicting the dynamic response of floors under multiple pedestrian walking loads. These methods can enhance the accuracy and reliability of vibration serviceability assessment for floor structures.