Floor Thickness Research Articles

Comparison of evaluations of human-induced floor vibration based on different design guidelines

This paper presents a comparative study on the evaluation of human-induced floor vibrations based on different design guidelines, including AISC DG11, ISO 10137:2007, SCI P354, and JGJT441–2019. Dynamic responses of floors are captured using FEM (Finite Element Method) simulations, with respect to varying thicknesses under different walking patterns and frequencies. The same single-step walking force model is applied across all scenarios to mitigate differences in floor comfort evaluation results due to varying walking force models, with a target to identify the differences induced by floor thicknesses, and walking patterns and frequencies. The dynamic responses are evaluated with respect to different evaluation indices in terms of floor comfort based on the adopted design guidelines. The findings reveal that resonance can occur even when the fundamental frequency of the floor is not equal to the walking frequency, but equal to (or very close to) an integral multiple of the walking frequency. The findings also reveal that walking patterns can affect the evaluation results of floor comfort, and walking at a fixed location may not give the worst evaluation scenario. Statistical analyses revealing the relationship between peak acceleration and floor thickness for walking at a fixed location can be mimicked using an exponential function, while for walking along fixed routes, a fifth-order polynomial function is more appropriate in depicting the relationship between peak acceleration and landing location. Comparison of the evaluation results indicates that different guidelines may give inconsistent or conflicting conclusions in terms of floor comfort, and among the adopted guidelines, ISO 10137:2007 imposes the strictest comfort requirements, while SCI P354 (VDV approach) offers the loosest criteria.

Safety evaluation method of bottom coal thickness in thick coal seam roadway

In recent years, the number of roadway floor rock burst accidents is increasing, which seriously restricts the safe production of the mine. Therefore, safety evaluation method of bottom coal thickness in thick coal seam roadway was studied. The research results shown that the stress concentration area of composite floor is distributed in coal seam or rock stratum with large elastic modulus. With the increase of floor rock strength, the stress of coal-rock composite floor increased gradually, but the displacement and energy decreased gradually. When floor rock strength was equal to bottom coal strength, the increase of floor stress and displacement with the change of bottom coal thickness was the smallest, which was 34.29% and 33.61% respectively. The elastic strain energy decreased from 14.58 to 9.85%. With the increase of bottom coal thickness, the stress and displacement of coal-rock composite floor increased first and then decreased, and the elastic strain energy decreased gradually. It puts forward the safety evaluation method of bottom coal thickness: floor failure depth → reasonable thickness of bottom coal → safety thickness of bottom coal. It can provide reference for design of roadway bottom coal retention and surrounding rock control in thick coal seam face.

Variations in pelvic floor thickness in relation to bony dimensions in South African women: using computed tomography scans

Pelvic floor disorders (PFDs) are a common reason for urogynaecological consultation around the world, especially in elderly women. These disorders have been associated with disruption to the structural integrity of the pelvic floor. This study explored whether there are variations in pelvic floor muscle (PFM) thickness in relation to parity, population group and age. Additionally, the study explored whether there were any correlations between PFM thickness and the bony pelvic parameters measured. This was a quantitative retrospective analysis of computerised tomography (CT) scans. A total of 125 CT scans of women belonging to black and white South African population groups were sampled from a tertiary hospital in Pretoria, South Africa. Statistical analyses were performed using Paleontological Statistics (PAST). A thicker pelvic floor was noted in black compared to white women. Pelvic floor thickness decreased with parity and age in both population groups. The intertuberous diameter, as well as the surface areas of the urogenital triangle and the perineum, were statistically significantly larger in white than in black women. Correlations between PFM thickness and bony dimensions were statistically significant for anteroposterior (AP) pelvic outlet diameter, where a greater AP outlet was associated with thinner PFMs in black women. Bony correlations with parity showed that the interspinous diameter in black women increased significantly with parity. The variations in bony pelvic dimensions and pelvic floor muscle thicknesses noted between population groups, in addition to the co-factors of parity and aging, will contribute to a better understanding of the anatomical reasons for incontinence.

Numerical analysis of the behaviour of a concrete floor in a steel-framed structure subject to a traveling fire

This paper presents a finite element model for a multi-story structure subjected to traveling fire. The structure selected has been previously investigated in experimental studies. The study investigates the effect of the number and positions of the panels exposed to fire on the fire behavior of the composite floor in the structure. Parameter analyses were conducted, including floor thickness, reinforcement arrangement, loads, position and number of panels exposed to fire, and traveling fire. The study shows that there are three different patterns of membrane action: ring type, diagonal U type, and opposite side U type. The moment and axial force of the steel beam near the fire panel increase gradually, while the internal force change of the steel beam at a distance from the panel exposed to fire is relatively small. The axial force of the edge and corner columns changed more significantly compared to the axial force of the middle column. Furthermore, the displacement, fire resistance, failure mode, and membrane action of the floors depend primarily on the position of the panels exposed to fire, the traveling fire, and the interaction among members.

On the vibroacoustics of cross-laminated timber embedded with acoustic black holes

The adoption of cross-laminated timber (CLT) in building construction is challenged by low-frequency impact noise. Conventional treatments typically involve increasing the mass of the floor assembly or employing structural decoupling techniques, both of which result in increased floor thickness. This study explores an alternative solution by examining the feasibility of embedding acoustic black holes (ABHs) into CLT floors. The ABH acts as a passive waveguide, concentrating vibrational energy in specific regions where it is transferred to damping layers and reduced. Using the finite element method, we investigated the vibroacoustic behavior of CLT plates within the 50–600 Hz frequency range. Our primary focus was on the influence of the ABH’s outer radius and the number of ABH inclusions within a CLT plate. The findings indicate that increasing the outer diameter of the ABH lowers the cut-on frequency and enhances the effective damping of the CLT plate. The increase in damping extends the effectiveness of the ABH to a broader frequency range, with the most noticeable effect above the cut-on frequency. The number of ABH inclusions impacts the structural modes below the cut-on frequency, and the optimal number of inclusions depends on the frequency of interest.

Optimization Analysis of Seismic Performance of Staggered Structure with Different Floor Thickness

Optimization Analysis of Seismic Performance of Staggered Structure with Different Floor Thickness

Prefabricated steel-concrete composite cross joints with concrete slab: Parameter analysis and theoretical study

Nowadays, many researchers are investigating prefabricated reinforced concrete composite structural systems due to their ability to achieve the double carbon goal, which aligns with the rapid development in the construction industry. This study proposes prefabricated steel–concrete composite joints with concrete slabs, termed prefabricated composite beam joints (PCBJs). Based on existing experiments, a three-dimensional solid model of PCBJs was developed using ABAQUS. From this model, the research evaluated the influence of axial compression ratio (n), floor slab width (w), floor thickness (t), and floor reinforcement ratio (ρ) on the hysteretic behavior of PCBJs, then examined the suitability of the bearing capacity calculation methods from JGJ 138-2016 and ANSI/AISC 360-16 for PCBJs. The results indicated that n and w significantly impact the hysteresis performance of PCBJs, whereas the influence of t and pis relatively small. When n exceeds 0.4, the larger the n, the worse the joint's plastic rotation ability. The calculation method for the flexural bearing capacity presented in the JGJ 138-2016 and the ANSI/AISC 360-16 are highly conservative. The modified formula for determining the flexural bearing capacity of composite beams considers gravity's second-order effect. These calculation outcomes align closely with the FEM results.

Analysis of mechanical performance of modular steel-concrete composite joints considering floor slab composite effects

This study establishes and verifies the finite element models (FEM) of MSCCJs to analyze the mechanical performance of modular steel–concrete composite joints (MSCCJs) under monotonic static load without considering the floor slab composite effect (FSCE). Subsequently, 12 MSCCJ models incorporating the FSCE are constructed using ABAQUS. The study evaluates the effects of varying column axial compression ratios (n = 0.15, 0.25, 0.4, 0.6), floor width (w = 800, 1200 mm), floor thickness (t = 90, 110, 120 mm), and floor reinforcement ratio (r = 6 %, 8 %, 12 %) on the bending moment, initial stiffness (k0), ductility, and stress transfer of the joints. The results indicated that as n increases, the shear stress concentration in the joint core module (JCM) and the steel framework at the lower column end become more pronounced. Concurrently, the bearing moment and k0 of the joint also increase. However, once n surpasses 0.4, the joint's plastic properties diminish upon damage. With an increment in w, the k0 and ductility deformation of the joint remain stable and then decline. At w = 1000 mm, the joint's bearing capacity, stress distribution, and deformation performance reach their optimum. Since it significantly impacts stress distribution, its effect on the joint's mechanical performance is minimal. Lastly, the value of r enhances the ductility of MSCCJs and the stress concentration in the reinforcement. It is advisable to maintain r between 1.1 % and 1.7 %.

Optimal log floor patterns

Multi-storey timber constructions predominantly employ engineered wood products as their primary materials. However, these materials undergo extensive processing, including cutting, grading, sorting, planing, and gluing, significantly increasing their cost and environmental impact. An alternative approach to promote the use of timber in construction is to use logs for columns, beams, and floors in buildings, taking advantage of the significant advancements in parametric design and robotics. Nevertheless, it presents specific challenges, such as developing appropriate designs for log connections and establishing protocols for their mechanical characterisation, which are beyond the scope of this research.The main focus of this article is to conduct a comparative examination of various layout patterns for log floors, aiming to minimise wood consumption and floor thickness. To obtain generalisable conclusions independent of parameters such as wood strength, loads or floor dimensions, an original optimisation method has been developed, inspired by morphological indicators. This article demonstrates that the conventional approach of using parallel joists along the shorter span may not always be advantageous. Instead, it highlights cost-effective solutions that enhance the value of smaller-diameter and shorter logs.

Developing simplified numerical calculation and BP neural network modeling for the cooling capacity in a radiant floor cooling system

ABSTRACT To upgrade the computational efficiency and ensure the accuracy of calculated cooling capacity of radiant cooling floor, this study proposed a simplified three-dimensional modeling by combining with a user-defined function compilation. The cooling capacity and minimum floor temperature were taken as evaluation indices considering different radiant floor thicknesses, layers’ thermal conductivities, pipe diameters, pipe spacing, and floor surface sizes. Moreover, a backpropagation neural network model and a prediction program were developed to quickly predict minimum floor temperature and cooling capacity. The results demonstrate that the established backpropagation neural network model can predict the values of cooling capacity and minimum floor temperature well, and the coefficients of determination were 0.9117 and 0.9435, respectively. With the thickness increase of cover layer and filling layer, the minimum floor temperature respectively increases by 10.97% and 11.01%. With the heat transfer coefficient increase of cover layer and filling layer, cooling capacity respectively increases by 30.56% and 23.46%. This study proposes an artificial intelligence method for the rapid prediction of cooling capacity and minimum floor temperature, and provides their theoretical support for engineering application.

Sound-insulation prediction model and multi-parameter optimisation design of the composite floor of a high-speed train based on machine learning

Designing a sound-insulation scheme for a composite structure efficiently and accurately for noise control in equipment is essential. However, traditional simulation and experimental methods for obtaining an optimal solution are not only time-consuming but also difficult to implement. In this paper, a sound insulation optimisation design method based on machine learning is proposed. The method is applied to design a complex composite floor structure of a high-speed train. By testing numerous practical schemes in the acoustics laboratory to obtain a sample set, a machine learning model for predicting the sound insulation performance of a composite floor of a high-speed train is trained and verified. Subsequently, an efficient and accurate multi-parameter sound insulation optimisation design of the composite floor structure based on the machine learning model is implemented. First, the original data samples required for model training are analysed and sorted. Second, the target feature subset is selected through the main influencing factor analysis, correlation-redundancy analysis, and mRMR feature selection calculation. Then, based on the SVR method, the standardised feature data are used to train and verify the sound-insulation prediction model of the composite floor structure of a high-speed train. Finally, two embodiments are presented to verify the advantages of the model in the multi-parameter optimisation design of the sound-insulation model of the composite floor structure of a high-speed train. The results show that the optimal sound insulation is 51.69 dB when the thickness and surface density of the composite floor are given. Similarly, the minimum surface density is 89.42 kg/m2 when the thickness and sound insulation limit are given.

Experimental And Numerical Comparison Of Shear And Buckling Of Metallic Beams With Circular Cuts In Their Webs

Cellular beams are becoming increasingly popular in metal construction due to their ability tomeet technical and economic constraints and reduce floor thickness. However, it's essential to complywith regulations to ensure stability and preserve structures. In this work, we focus on the experimentaland theoretical results of shear and buckling of IPE A 100 cellular beams with circular cuts in their webssubjected to a concentrated load. Results show that vertical displacement induced by transversecompression is affected by length, cuts in the web, load location, and beam stiffening. Comparison ofexperimental and theoretical results highlights the importance of conducting experimental tests to validatetheoretical outcomes and ensure prediction accuracy

Влияние реконструктивной рубки в лиственно-еловом древостое на корневую конкуренцию пород

The predominance of mixed forest stands in a productive forest fund, which is located in the middle taiga subzone of Northwest Russia, determines the relevance of an investigation of the growth and development characteristics of the trees. In secondary stands, created by an extensive human consumption of primary spruce stands, spruce trees are generally presented in a minor quantity. The recovery of their dominance is an urgent economic and ecological issue. Despite the unity of approaches concerning the maintenance of deciduous-spruce forests, the research characteristics on the structure of the root systems differ considerably along with age and geographical position. This article investigates a root system competition between spruce and deciduous species in a 70-year-old blueberry-type forest that was 100 thinning by a reconstructive cutting 35 years ago. The mass of fine roots and their distribution in the upper solid layers were examined by the method of soil monoliths in the mixed stands with different proportions of spruce. The numerical characteristics of the stands were determined by the results of a regular complete enumeration on the trail plots. Besides, the tree diameters were measured around the circular plots, which were made for the collection of the monoliths. The records were made on the dynamics of changes in forest floor thickness and vegetation. The relationship between the underground and elevated parts of the stands was explored. It was shown that the roots of spruce can occupy the same ecological niche as the roots of deciduous species. A correlation analysis revealed a statistically significant relationship between the mass of fine spruce roots and the competitive influence of deciduous species, the proportion of spruce in the stand, and its current volume increment. There was a significant difference in spruce root mass under joint growth with birch and aspen. Therefore, it was concluded that this phenomenon has a complex nature. Namely, the mass of the spruce roots has a direct dependency on their closeness to the maternal trees in combination with the spatial heterogeneity of the organic soil layers. The gained findings are important for the regulation of the composition and structure of the mixed deciduous-spruce stands for growing sustainable stands with a high economic value. For citation: Karpechko A.Yu., Sinkevich S.M. Influence of Reconstructive Cutting in Deciduous-Spruce Stands on Root Competition of Species. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 3, pp. 99–112. (In Russ.). https://doi.org/10.37482/0536-1036-2023-3-99-112

Optimizing composite floors for sustainability and efficiency: Cross laminated timber, concrete types, and ductile notch connectors with enhanced shape

Timber-concrete composite (TCC) structures allow designing efficient building floors in terms of lightness, slenderness, and acoustic insulation. The late development of ductile notch connectors has further advanced TCC structures. This work aims to further optimize the shape of ductile notch connections and to optimally design TCC floors with minimum embodied carbon, floor thickness, self-weight and cost.Firstly, an experimental campaign was carried out to characterize the shear behavior of ductile notch connectors with different shapes, which varied from rectangular to trapezoidal to avoid the use of screws, and concrete types, which varied from normal concrete to ultra-high performance fiber reinforced concrete. For the sake of comparison, a glued connection was also considered. Then, a multi-criteria optimization method was performed to optimally design TCC floor with the developed notch connectors and concrete types. The latest design recommendations for TCC floors developed in Canada were considered. A Non-Linear Finite Element Analysis (NLFEA) was carried out for validation. The presented results push the current design limits in terms of embodied carbon and volume of construction materials towards climate-positive floors.

Basement Design for Vibration Reduction of High-Rise Buildings under Metro Operation

Vibration induced by metro operation on the underground line is transmitted to the buildings above the line, which adversely affects on the normal life and work of human in the building. To study this problem, based on the plate-shell vibration theory, a plate-column-plate coupled model is constructed to analyze the influence of plate thickness, plate elastic modulus and column arrangement on the vibration in mechanism firstly. Relying on a practical engineering problem, two models are established, namely a train-track coupled dynamic model and a monolithic track bed-tunnel-soil-building model, loading fastener force from the train-track coupled dynamic model on the monolithic track bed, vibration propagates to high-rise building through soil-building coupling. Field test is conducted to verify the reliability of the numerical model. On the basis, the vibration law of building under different basement floor thicknesses, basement floor material and arrangement of non-permanent columns are studied. Results show that changing the basement design parameters has different effects. The Z vibration level of building floor decreases with the increase of basement floor thickness. Basement floor thickness increases by 0.02 m, the Z vibration level of the floor decreased by 1.4–2.2 dB at most. The decrease of elastic modulus leads to a slight decrease of the Z vibration level of building, the change is less than 1 dB. Without changing the arrangement of basement load-bearing columns, reducing non-permanent structural columns significantly reduces the Z vibration level, with attenuation of up to 5.1 dB.

Research on Floor Heave Mechanisms and Control Technology for Deep Dynamic Pressure Roadways

In order to study the influencing factors of floor deformation and floor heave mechanisms of deep mining roadways, this paper takes the deep dynamic pressure mining roadway of a mine as the engineering background and adopts a research method combining theoretical analyses, numerical simulations and field observations to study the influence of various factors on floor deformation and floor heave mechanisms. It is determined that the influencing factors on floor heave are a large buried depth, a long duration of dynamic pressure, unique characteristics of the surrounding rock and an insufficient support strength. A bearing mechanics model of the roadway floor beam is established, and it is determined that the displacement of the roadway floor is negatively correlated with the elastic modulus and floor thickness and positively correlated with the buried depth of roadway, the roadway width and the width of fracture zone. A numerical simulation method is used to study the influence of the original geological conditions, strengthening the elastic modulus of floor, strengthening the strength of the side wall rock and increasing the thickness of the floor rock on the displacement of the roadway floor. It is determined that increasing the thickness of floor rock controls the floor heave the most, followed by strengthening the elastic modulus of the floor rock and then strengthening the strength of the side walls. The results of the numerical simulation agree well with those of the theoretical analysis. After the control method of “bottom lifting + bottom angle bolt + floor bolt ” is adopted on site to treat the floor heave, the floor heave volume of the roadway is small during the service period of the 303 working face return air roadway, which meets the application requirements of the roadway. Meanwhile, the theoretical analysis and numerical simulation results are indirectly verified.

Vibration Serviceability of Large-Span Steel–Concrete Composite Beam with Precast Hollow Core Slabs Under Walking Impact

A large-span steel–concrete composite beam with precast hollow core slabs (CBHCSs) is a relatively new floor structure that can be applied to various long-span structures. However, human-induced vibrations may present serviceability issues in such structures. To alleviate vibrations, both the walking forces excited by humans and the associated floor responses must be elucidated. In this study, 150 load–time histories of walking, excited by 25 test participants, are obtained using a force measuring plate. The dynamic loading factors and phase angles in the Fourier series functions for one-step walking are determined. Subsequently, walking tests are performed on seven CBHCS specimens to capture the essential dynamic properties of mode shapes, natural frequencies, damping ratios, and acceleration time histories. The CBHCS floor system generally exhibits a high frequency (> 10 Hz) and low damping (damping ratio < 2%). Sensitivity studies using the finite element method are conducted to investigate the vibration performance of the CBHCS floor system, where the floor thickness, steel beam type, contact time, and human weight are considered. Finally, analytical expressions derived for the fundamental frequency and peak acceleration agree well with the experimental results and are hence proposed for practical use.

Maximum displacement prediction of composite floor system under falling impact

Analytical and numerical investigations on the maximum displacement of the steel-concrete composite floor system subjected to falling impact are presented in this paper. Explicit formulae are established to compute the floor maximum displacement under impacts with different kinetic energy transfer ratios. Parametric analyses are conducted to study the influence of impactor mass, impact height, floor longitudinal span, floor thickness, rebar diameter, beam depth, and coefficient of restitution on the maximum displacement of floor. Associated practical recommendations are also proposed for determining the maximum displacement of floor under falling impact. It is found that in fully elastic impact, the maximum displacement is highly sensitive to the impact height, whereas in fully plastic impact, the value is significantly affected by the impactor mass. The upper-bound estimation of the displacement can be achieved by using fully elastic impact model. However, fully plastic impact model should be adopted when the impactor mass increases to more than 30 % of the total mass of the floor.

Fused Deposition Modelling 3D Printed Immediate Release Tablets – Understanding the Impact of Printer Parameters

The aim of this study was to prepare tablets that offer an immediate release (IR) of the loaded active ingredient using fused deposition modelling (FDM) 3D printing. Hydrochlorothiazide (HCTZ) was used as a model drug, with polyvinyl alcohol (PVA) as the primary polymeric carrier and sorbitol as a plasticizer. The impact of printer parameters, including infill density, roof and floor (R&amp;amp;F) thickness and nozzle size, on the drug release properties of printed tablets was investigated. The results support the use of FDM-3DP as an approach to manufacture IR tablets and highlighted the importance of the printing design on drug release properties.

Screening criteria of underground coal gasification (UCG): a case study from Mangunjaya Area, South Sumatra Basin, Indonesia

Underground coal gasification (UCG) is a technology that can increase the value of coal. This technology turns coal into gas below the surface through the gasification process. UCG offers many applications for power generation, heating, and the chemical industry. The Mangunjaya area is one prospecting area, located in the South Sumatra Basin, which has been actively producing coal for a long time. This study focused on determining the potential location of UCG in Mangunjaya. Screening criteria were extracted from previous studies including coal thickness, depth of the coal seam, depth and thickness ratio, coal rank, the dip of a coal seam, roof and floor rock type and thickness, and geological structure. Thirteen boreholes were examined to determine their potential, namely MJ1 to MJ13. The evaluation results show that the Mangus coal seam at a depth of 260,4 meters in the MJ2 borehole and the surrounding area in 15 km2, matches the criteria and has the most potential coal for UCG development.