Floor Assemblies Research Articles

Arrangement of reinforcement in variable density timber slab systems for multi-story construction

The arrangement of columns and their spacing in multi-story timber construction is restricted to rectangular grids by the production and shipping sizes of floor assemblies. This is particularly true for hollow box floor systems, for which the punctual supports must be placed at the reinforced edges of the hollow boxes. The arrangement of the columns and their spacing is thereby restricted by the production and shipping sizes of the box ceilings to rectangular grids. To overcome these design limits a new wooden box building system is developed that allows for irregular column layouts through a tailored slab interior design. This development allows for the increased applicability of timber floor systems regardless of site shape or architectural design intent. The slab interior design is dependent on occurring forces and fabrication requirements. Three methods for the internal slab layout are developed and compared: a sequential method, a structurally informed agent-based method, and a geometrically informed agent-based method that uses both a sequential and agent-based approach. The structural performance of each method is compared through the analysis of three reinforcement layouts an architectural testing setup.

Modeling evaluation for fire resistance design of rail car floor assembly

This paper is prepared to report the engineering practice by a Chinese railcar manufacture in a railcar design process for a Metro system in U.S. The fire resistance of rail car floor systems is considered as one of the important fire protection features on the railcars operated in U.S., which provides fire separation between the equipment installed under the floor and the passengers insider railcar. In this study, a pragmatic approach was developed to numerically evaluate the fire resistance of rail car floor assemblies and provide insights for necessary design modifications. Finite element analysis (FEA) was applied to assess the fire resistance performance of a rail car floor assembly designed for a metro railway system in the U.S. An optimization algorithm was applied to obtain the thermal properties of intumescent coating. FEA analysis results were applied to assist the design modifications so that the floor assembly successfully satisfies the current requirement and passes the ASTM E119 fire resistance test. The FEA modeling details and heat transfer analysis results are presented. It is also shown that the model predictions agree conservatively well with the full-scale fire resistance test data.

In situ testing methods for evaluating and predicting the impact isolation of high-performance floating floors - Part 2

Floating floors using discrete isolators are commonly recommended to mitigate impact noise from fitness facilities; however, there has been little study of the performance of floating floors under the types of heavy/hard impacts that often cause noise and vibration complaints from fitness facilities. Furthermore, it can be difficult to create mock-ups of floating floor systems for in-situ testing, making it difficult to adequately evaluate their performance. Here, the authors present the beginnings of a research program intended to develop effective methods for evaluating and predicting the performance of floating floors using in-situ testing methods. Part 2 of the presentation covers the results of the measurements, including the effects of the following changes to the floating floor assembly: various air cavity depths, vented vs. un-vented air cavities, loaded vs. un-loaded floors, and concrete versus plywood floors. Finally, Part 2 presents the intended next steps in the research program.

Quantitative comparisons of resilient channel designs in walls and ceilings

Resilient channel is common within lightweight construction to improve the airborne and impact noise isolation of wall and floor-ceiling assemblies. The authors have previously presented results from systematic studies of resilient channels in wood stud wall assemblies (Internoise 2009; International Congress on Acoustics 2010) and wood-joist floor assemblies (International Congress on Sound and Vibration 2015) in which the effect of brand and model of resilient channel was compared in various assemblies. These studies documented the clear and significant acoustical performance differences between makes and models of channel that would have been considered equivalent before the release of this work. Additional comparative studies have been performed adding to the data previously presented. Acoustical performance is compared and conclusions about products are presented.

Horizontal impact sound transmission measurements

Impact sound transmission is typically considered for the floor/ceiling assembly that separates vertically stacked spaces. This is the context that ASTM E492 laboratory testing and ASTM E1007 field testing are performed. However, impact sounds often have the potential for causing significant flanking transmission through structural connections of the floor system to surrounding spaces. A common concern for possible impact sound transmission can occur with hard flooring finishes that are not isolated from the floor structure to adjacent spaces. For this condition, while it is possible to achieve adequate impact isolation vertically by using isolated ceiling assemblies, the lack of isolation for the flooring may allow significant horizontal impact sound transmission, which is not affected by the ceiling assembly. This study presents findings and comparisons from measurements of impact sound transmission testing between horizontally adjacent spaces on a concrete floor slab and a wood-framed floor assembly with different flooring underlayment conditions.

Separating function of timber floor and wall assemblies

Abstract The basic concern on the fire compartmentation is focused on to limit the spread of the fire and smoke outside of the room of the fire origin. Where the fire compartmentation is required, the elements forming the boundaries of the fire compartment should be designed and constructed in such a way that they maintain their separating function during the relevant fire exposure [1]. The general accepted method for assessing the fire resistance of a structural or non-structural member is the full-scale testing of the fire performance, however, several calculation methods for verification of the separation function of timber assemblies can also be used in order to prove compliance with the code regulations [2].

Wisconsin assembly passes Psychology Interjurisdictional Compact bill

The Wisconsin assembly on Jan. 20 passed State Rep. Paul Tittl's (R‐Manitowoc) Assembly Bill 537 to provide greater opportunity for people in Wisconsin to receive needed mental health help, Wispolitics.com reported. The Psychology Interjurisdictional Compact (PSYPACT) provides greater opportunity for people in Wisconsin to receive needed mental health help. It does so by allowing psychologists to practice either in person or other than in person across state lines in states that have enacted the compact. As a result, quick and efficient access to mental health resources will be greatly increased. “The mental health needs in Wisconsin are great, and the COVID situation has increased the number of people in need of psychological services,” said Rep. Tittl. “This bill makes it easier for them to receive help.” The benefits of joining PSYPACT increases access to rural Wisconsinites served by psychologists out of state, provides treatment to patients needing care by a specialist who is not available in Wisconsin, enables sports psychologists to travel with and provide services to a team and allows a Wisconsinite temporarily moving out of state to continue to receive care from a psychologist in Wisconsin. Currently, 27 states have enacted PSYPACT, including Illinois and Minnesota. As more states enact PSYPACT, it will become even more effective in alleviating mental health care shortages and improving access to mental health services. The bill received bipartisan support and passed during the Assembly floor session. It now awaits scheduling in the Senate.

Quasi-Static and Fatigue Properties of Thermoset Sandwiches with 3D Continuous Fibre Reinforced Polyurethane Foam Core.

Innovative materials for substituting metals are required to reduce the mass of moving components. This decreases the CO2 emissions of overall systems. A thermoset sandwich for high mechanical properties and thermal insulation is presented in this paper. It has an innovative 3D continuous reinforced core, which allows the optimisation of the substance exploitation by wide-ranging possibilities of fibre orientation. This was demonstrated with three sandwich variants. The reference had no core reinforcement and the other two were reinforced with different spacer fabrics. The process chain for the manufacturing consists of Structural Reaction Injection Moulding (SRIM) and Vacuum Assisted Resin Transfer Moulding (VARTM). Significant increases in absolute as well as specific characteristic values were demonstrated by the reinforcement in a compression and bending test. It was also shown that quasi-static characteristic values under fatigue loading are maintained to a greater extent with the core reinforcement. The sandwich material was applied as a floor assembly for a snow groomer. The design was tailor-made for the mechanical, thermal and acoustic requirements. This proved the transferability of the process chain for manufacturing samples to the production of large-volume components with complex geometry.

Sustainable early design exploration of mid-rise office buildings with different subsystems using comparative life cycle assessment

Minimizing environmental impacts over a building's life cycle is critical to achieving sustainable communities. Early design is the most critical step to improve construction's sustainability, as the majority of important decisions have not yet been made. However, the implementation of sustainability assessment in early design is data- and effort-intensive, resulting in limited whole building life cycle assessments. Previous studies have mainly focused either on single residential structures, included only a subset of building components, or investigated early design parameters mostly associated with energy efficiency. Whereas, comparison of alternative building subsystems at early design received less attention. This study aims to provide and utilize benchmark data for the life-cycle impacts of mid-rise office buildings, focusing on the impact of building subsystem selection at early design exploration. Environmental impacts were compared across six professionally-designed archetypes comprising compatible combinations of foundation, floor, and structural assemblies for a site in Charleston, South Carolina. Detailed operational energy modeling was performed using the EnergyPlus framework, where a range of code-compliant envelope systems are studied and paired with other assemblies. Lastly, sensitivity assessment and statistical analysis are performed to quantify uncertainty associated with the use of such data for early design guidance. The results suggest that decisions associated with the use phase (such as envelope selection) dominates life cycle impacts and should be prioritized. Additionally, no single subsystem governs all embodied impacts across different buildings. Lastly, it is critical to consider a large number of alternatives at the early design stage, as excluding a combination of subsystems might close pathways to reaching a more environmentally suitable alternative during design iterations/optimization.

Thermal retrofitting for sustainable use of traditional dwellings in Mediterranean climate of southwestern Anatolia

Thermal retrofitting implementations are crucial for safeguarding the functional sustainability of historical buildings as they can improve the thermal performance of these buildings while maintaining thermal comfort for their occupants. This study aims to examine the thermal behavior of a common historical building type in Anatolia / Turkey, the traditional houses with exterior hall (sofa), and to determine enhancement potentials of possible thermal interventions. Research method consists of on-site thermal measurements, laboratory analyses on traditional construction materials and transient thermal analyses utilizing simulations on DesignBuilder software. Study cases were selected from both urban and rural sub-settlements. The results demonstrated that the thermal insulation works within floor assemblies, airtightness measures, adding secondary glazing to windows and suggesting transparent circulation corridors provide significant energy improvements. These interventions would save 26.5% of building energy consumption in the urban and 30.4% in the rural sub-settlements when applied together. Furthermore, when the integration of a modern HVAC system, ground-source heat pump is implemented, these improvement rates can be increased to more than 60%. Consequently, it was determined that the cases have significant potentials for thermal enhancements which renders the application of thermal interventions as a capable conservation tool.

Experimental study on fire resistance of a full-scale composite floor assembly in a two-story steel framed building

PurposeThe purpose of this paper is to report the first of four planned fire experiments on the 9.1 × 6.1 m steel composite floor assembly as part of the two-story steel framed building constructed at the National Fire Research Laboratory.Design/methodology/approachThe fire experiment was aimed to quantify the fire resistance and behavior of full-scale steel–concrete composite floor systems commonly built in the USA. The test floor assembly, designed and constructed for the 2-h fire resistance rating, was tested to failure under a natural gas fueled compartment fire and simultaneously applied mechanical loads.FindingsAlthough the protected steel beams and girders achieved matching or superior performance compared to the prescribed limits of temperatures and displacements used in standard fire testing, the composite slab developed a central breach approximately at a half of the specified rating period. A minimum area of the shrinkage reinforcement (60 mm2/m) currently permitted in the US construction practice may be insufficient to maintain structural integrity of a full-scale composite floor system under the 2-h standard fire exposure.Originality/valueThis work was the first-of-kind fire experiment conducted in the USA to study the full system-level structural performance of a composite floor system subjected to compartment fire using natural gas as fuel to mimic a standard fire environment.

Behavior of Composite Floor Assemblies Subject to Fire: Influence of Slab Reinforcement

AbstractA series of fire experiments are being conducted on the 2‐story steel framed building with composite floors in the National Fire Research Laboratory. This paper presents a brief overview of experimental design and discusses some results of the first test conducted on 6.1 m by 9.1 m composite floor assembly exposed to a standard fire. The test floor slab was constructed with lightweight concrete cast on 7.7 cm deep formed steel deck units and welded wire fabric (60 mm/m2) as the minimum shrinkage reinforcement required in the U.S. practice. The structural steel beams and girders were sprayed with a cementitious fire resistive material for a 2‐hour restrained fire resistance rating. While the test floor assembly resisted mechanical loads (2.7 kN/m2) applied using hydraulic actuators, its underside was exposed to a natural gas‐fueled compartment fire that was equivalent to the standard gas temperature‐time relationship. The study revealed that the test floor assembly could withstand an imposed load at a large vertical deflection on the order of span / 16, but the concrete slab failed due to limited ductility and strength prior to 2 hours in a standard fire. Simple post‐test predictions were performed incorporating tensile membrane action in the floor slab to compare with the measured behavior. Limited comparisons discuss the contribution of steel decking and slab reinforcement to the load‐carrying capacity of a floor assembly in fire.

Digital twin-based research on the prediction method for the complex product assembly abnormal events

ABSTRACT The emergence of abnormal events (e.g. personnel abnormalities, equipment failures, etc.) on the assembly floor of complex products can seriously affect normal assembly progress. In response to the problems of poor timeliness and lack of predictability in the control of abnormal events on the assembly floor, a method for predicting abnormal events on the assembly floor of complex products based on digital twin technology is proposed. A model for predicting abnormal assembly events is constructed with the physical assembly workshop, virtual assembly workshop, assembly workshop twin data platform and abnormal events prediction service system working together, and its prediction operation mechanism is designed based on the classification of abnormal events and the workflow of the mechanism under different states is analysed. The Grey-Markov method is used to predict abnormal assembly events and provide real-time information for the planning and scheduling system. In order to verify the effectiveness of this scheme, combined with the electrical multiple units bogie assembly workshop, the prediction of the number of equipment failures at the bottleneck station is achieved. The prediction accuracy is much better than that of the GM(1,1) model and can be applied to actual production.

Apparent impact sound insulation performance of cross laminated timber floors with floating concrete toppings

Mass timber buildings are gaining increasing popularity as a sustainable alternative to concrete and steel structures. Mass timber panels, especially cross-laminated timber (CLT), are often used as floors due to their dry and fast construction. CLT has poor impact sound insulation performance due to its lightweight and relatively high bending stiffness. Floating concrete toppings are often applied to increase both the airborne and impact sound insulation performance. However, the impact sound insulation performance of floating concrete toppings on CLT structural floors is affected by both the concrete thickness and resilient interlayer. This study investigated the efficiency of both continuous and discrete floating floor assemblies through mock-up building tests using small-scale concrete toppings according to ASTM E1007-16. It was found that the improvements by continuous floating floor assemblies are dependent on the concrete thicknesses and dynamic stiffness of resilient interlayers. The improvements cannot be well predicted by the equations developed for concrete structural floors. The highest apparent impact sound insulation class (AIIC) achieved with continuous floating floor assemblies in this study was 53 dBA, while that of the discrete floating floor assemblies was up to 62 dBA. The discrete floating floor solution showed great potential for use in mass timber buildings due to the high performance with thinner concrete toppings.

Acoustic design tools for estimation of sound insulation performance of wood wall and floor assemblies

The National Building Code of Canada 2015 stipulates the minimum requirements of the airborne sound insulation transmission through common interior walls and ceiling/floor assemblies. The required minimum Apparent Sound Transmission Class (ASTC) is 47 in Canada, whereas the Impact Insulation Class (IIC) for floors is recommended to be higher than 55. For many years, significant efforts were made to develop sound insulation prediction models or tools to predict the sound insulation performance of wall and floor/ceiling assemblies at the design phase in order to meet the requirements and the recommendations made by codes. However, today few models can provide a reliable acoustics design tool. In this document, three prediction tools thought to be practically useful are presented and evaluated. Between these three prediction tools, one is an analytical model of the Insul software while the other two are empirical models developed by the National Research Council of Canada and the American Wood Council. This paper compared the STC and IIC ratings of wood wall and floor assemblies estimated by these three models and verified them by the measured STC and IIC ratings. This work aims at providing an idea for readers to choose a suitable design tool to proceed with their acoustic designs.

Edgewise Compressive Behavior of Composite Structural Insulated Panels with Magnesium Oxide Board Facings.

Edgewise compression response of a composite structural insulated panel (CSIP) with magnesium oxide board facings was investigated. The discussed CSIP is a novel multifunctional sandwich panel introduced to the housing industry as a part of the wall, floor, and roof assemblies. The study aims to propose a computational tool for reliable prediction of failure modes of CSIPs subjected to concentric and eccentric axial loads. An advanced numerical model was proposed that includes geometrical and material nonlinearity as well as incorporates the material bimodularity effect to achieve accurate and versatile failure mode prediction capability. Laboratory tests on small-scale CSIP samples of three different slenderness ratios and full-scale panels loaded with three different eccentricity values were carried out, and the test data were compared with numerical results for validation. The finite element (FE) model successfully captured CSIP’s inelastic response in uniaxial compression and when flexural action was introduced by eccentric loads or buckling and predicted all failure modes correctly. The comprehensive validation showed that the proposed approach could be considered a robust and versatile aid in CSIP design.

Experimental study of earthquake-resilient prefabricated opening-web steel channel beam-column joint with double FCPs

In order to facilitate floor assembly and pipeline paving, this paper puts forward a new kind of prefabricated opening-web steel channel beam-column joint with double flange cover plates (POWSCBCJ) which is based on the design concept of plastic damage concentration and replaceable damage components. Six quasi-static reciprocating loading tests were carried out on four joints, and the hysteretic curves, skeleton curves, slip curves and strain curves of each specimen were obtained. The effects of thickness of flange cover plate (FCP), the quantity of connecting bolts and the bolts spacing of FCP and other parameters on the seismic performance and post-earthquake repairable performance of the joint are mainly investigated, and the post-earthquake repairable function, and fatigue performance of the joint under low-cycle reciprocating load are evaluated. Experimental study shows that this kind of joint has good bearing capacity, seismic performance and low-cycle fatigue performance. The joint can transfer the plastic hinge to the replaced FCP by strengthening the flange of the cantilever beam and weakening the FCP, so as to protect the major components such as beams and columns, and the joint function can be quickly repaired by replacing the energy dissipation components after earthquake; the repaired joint also has good bearing capacity and seismic capacity. Each design parameter has great influence on the bearing capacity and energy dissipation capacity of the joint.

Use of Nesting Workstations in Assembly

Abstract Over the years there has been a fixed idea that components just enter the assembly floor and that assembled products leave it subsequently after certain operations have been executed on such products. Besides, there is a common notion that only small and simple products can be assembled on the so called “assembly nests”; however, the dimensions of objects assembled inside these keep increasing. Nowadays, even an aircraft, a boat, etc. can also be assembled on a moving trolley. This is possible given to the fact that the trolley with the product and with the operators themselves may come to the same storage of parts, while the system does not need to be balanced in time. On the other hand, in assembly nested layouts, the productivity of one operator is usually higher than the productivity on the line station and this because such lines are not often time balanced. Besides, this is also enhanced by the fact that more than one operator can work on a single nest. In this regard, the present paper seeks to identify the ways of combining or assembling components into products, and to analyse quality of the abovementioned assembly approaches.

Fire resistance behaviour of LSF floor-ceiling configurations

Light gauge Steel Frame (LSF) floor-ceiling systems made of thin-walled cold-formed steel structural members deliver innovative, lightweight and cost effective solutions for many floor assemblies. However, the mechanical properties of cold-formed steel structural members deteriorate in fire. Hence fire rated gypsum plasterboard ceilings are required to protect them and avoid premature failures of floor assemblies. However, the behaviour of LSF floor-ceiling systems in fire is not well understood. Hence a series of small-scale standard fire tests was undertaken to investigate the fire resistance of cold-formed LSF floor-ceiling systems of varying configurations. Configurations included structural plywood as the subfloor, gypsum plasterboard ceilings, thin steel sheathing, different joist sections such as lipped channel beam and rivet fastened rectangular hollow flange channel beam and rockwool cavity insulation. The effects of these parameters on the fire resistance of LSF floor-ceiling assemblies are discussed in this paper. Fire resistance improvements of 21–32% were observed when steel sheathing was used in varying configurations. This shows the potential of using thin steel sheathing below the gypsum plasterboard that enhanced the insulation failure times by resisting gypsum plasterboard fall-off. However, cavity insulation led to reduced fire resistance times while plywood subfloors exhibited rapid decomposition and burning when the temperature exceeded 234°C. This paper presents the details of the small-scale standard fire tests of LSF floor-ceiling systems of varying configurations and the results in terms of time-temperature curves and fire resistance times.

Developing mathematical model and optimization algorithm for designing energy efficient semi-automated assembly line

In this study, a new extension of the semi-automated assembly line designing problem is presented. The main difference between this paper and existing work is that the energy consumption, smoothness index and total cost are all taken into consideration. The tasks can be performed by more than one format in the semi-automated assembly line, which means the operation time and energy consumption of tasks depend on the allocated stations. To obtain the trade-off among three objectives. First, a mathematical model with constraints is provided. Then, an improved whale optimization algorithm (IWOA) is presented, the chaotic maps, variable neighborhood search (VNS) and mutation are adopted to enhance the algorithm performance. In order to demonstrate the effectiveness of the algorithm and employed mechanisms, numerical comparison experiments are accordingly conducted. The results show that the specific designed algorithm outperforms five other well-known algorithms in solving the energy-oriented semi-automated assembly line designing problem. At last, the managerial insights are provided based on the sensitivity analysis. And a real case derives from car floor assembly system is used for validation of the proposed model and algorithm.