Composite Floor Research Articles

Experimental and numerical study on the in-plane behaviour of a new long-span assembly composite floor system under lateral load

ABSTRACT A new long-span assembly composite floor system for use in multi-column frame-tube structure is presented. The basic assembly unit consists of steel truss keel and profile sheet concrete composite slab, which of the two parts are combined together through shear stud. By means of standardized assembly connection structure, such a new floor system can realize a rapid assembly of floor and support frame. Based on test research of 1/3 scale model, the paper discusses the in-plane mechanical performance of the new floor system. Through loading at the direction of parallel to the assembly slab seam and perpendicular to the assembly slab seam, respectively, the influence of assembly orientation of floor units on the failure modes, distribution and transmission performance of the horizontal loads, and the in-plane stiffness were identified in detail. A numerical model was developed with its input parameters calibrated from full-scale experimental tests. Based on model analysis, the influence of thickness of concrete slab on the in-plane stiffness was discussed.

Artificial Intelligence for Developing Accurate Preliminary Cost Estimates for Composite Flooring Systems of Multi-Storey Buildings

ABSTRACT In a decision-making study, design alternatives are compared with respect to cost, performance, and reliability, and the best is selected. Often, due to the time constraints imposed by the design schedule and budget restrictions, the number of design alternatives considered is limited. This research focuses on composite flooring systems for multistory buildings and the application of value techniques to the construction industry. The study uses data that obtained from the RSMeans Assemblies Books for the period 1997–2019. The data obtained from RSMeans consists of assembly cost ($/sf of floor) as the dependent variable; and the structural span (ft.), superimposed load (p.s.f), unit cost of sheet metal ($/LF of sheet), unit cost of concrete ($/CY), unit cost of steel structural ($/ton), and total load (p.s.f) as the independent variables. A simple computer model is designed for recommending the optimal composite flooring system of a multistory building, during the preliminary design stage. The value engineering (VE) team to achieve the VE goals mentioned above can use the model.

Standardization ofhigh‐temperaturespecific heat capacity test parameters offire‐resistantgypsum board

SummaryThe specific heat capacity at the high temperature of fire‐resistant gypsum boards plays a vital role in the simulation accuracy of the thermal response for cold‐formed steel (CFS) composite structures. However, there are not given comprehensive and accurate values in the existing standard for test parameters (including heating rate, sample quality, and sample size) used in the test of the specific heat capacity of gypsum boards. This situation leads to large differences in test results. This paper aimed to provide standardized test parameters for obtaining accurate specific heat capacity curves of gypsum boards. First, the effect of test parameters was quantified by 10 groups of specific heat capacity tests of gypsum boards through the uniform design; Then, the standardized values of test parameters were proposed combined with sample composition analysis and finite element numerical analysis: the heating rate was 12°C/min, the sample mass was 18 mg, the sample particle size was 45 to 48 μm; Finally, the standardized test parameters were verified by comparing with the test results of cold‐formed steel composite floors in the literature. The results show that the specific heat capacity curve of gypsum boards measured by the standardized test parameters proposed to this paper has good accuracy for simulating the time‐temperature curve of cold‐formed steel composite floors. It is conducive to accurately assess the fire resistance of cold‐formed steel composite floors. The test parameter standardization method can also be extended to other building materials. As a result, the specific heat capacity test can follow a basic standard.

Study on Structural Design and Manufacturing of Sandwich Composite Floor for Automotive Structure

In this work, structural design and manufacturing of sandwich composite floor for automobile was performed. The tensile and compression strength of specimen were investigated. Based on this, structural design of floor board was performed. The sandwich composite floor board are subject to payload. The maximum load was analyzed in consideration of the safety factor. The structural design and analysis were performed in consideration of applied load. The finite element analysis method was applied to investigate structural safety. The stress, displacement, and buckling analysis was carried out. Through the structural analysis, it was confirmed that the designed floor board structure is safety. Based on the result, the manufacturing of prototype was conducted. Finally, test and evaluation of composite floor board was performed.

Experimental and Numerical Study on the Flexural Performance of Assembled Steel-Wood Composite Slab

This paper presents research on a new type of fabricated steel–wood composite floor material in the style of a slab-embedded beam flange, using test methods and finite element numerical analysis to study the flexural load-bearing performance of the composite slabs. Through experimental phenomena, the failure process and mechanism of the composite floor are analyzed, and the deformation performance and ultimate bearing capacity of the composite floor material are assessed. Through numerical analysis of the finite element model, the influence of the connection mode of the floor and the composite beam, the type and number of connectors, and the width of the flange of the composite beam on the bending performance of the composite beam–slab system is studied. The research results show that the fabricated steel–wood composite floor slab has good load-bearing and deformation performance. The self-tapping screw connection of the floor slab is better than the ordinary steel nail connection, and the reasonable screw spacing is 100–150 mm. Increasing the flange width of the composite beam can significantly improve the load-bearing capacity of the steel–wood composite floor component.

Development of cross laminated timber-cold-formed steel composite beam for floor system to sustainable modular building construction

Cold-formed steel (CFS) and cross-laminated timber (CLT) structural components are widely employed in low- to mid-rise and modular building constructions. These two materials have individually shown to be lightweight, and possess relatively higher strength characteristics. Owing to these benefits, composite CLT-CFS sections can be used as structural elements and possibly be employed in modular buildings with enhanced structural performances. This paper presents the development of CLT-CFS composite beam for the floor system in modular buildings and investigates the structural performances through finite element (FE) analyses. Initially, the FE models of CFS beam and CLT panel were developed and validated with experimental results. Validated models were used to develop the FE model of CLT-CFS composite beam for the floor system. Results of FE analyses of the CLT-CFS composite floor systems showed that considerable benefits in terms of structural response can be achieved due to the mobilisation of composite action. For the CLT-CFS system investigated in this research, about 20% of enhancement in moment capacity was found. The presented study leads a path to highlight the gains in the structural performance of CLT-CFS composite beams floor system and it is a prospective option to be employed in sustainable modular building construction.

Sustainability Design Considerations for Timber-Concrete Composite Floor Systems

Over the last few decades, there has been growing interest in the use of low-carbon materials to reduce the environmental impacts of the construction industry. The advent of mass timber panels (MTP), such as cross laminated timber (CLT), has allowed structural engineers to specify a low-carbon material for a variety of floor design considerations. However, serviceability issues such as vibration and deflection are limiting the construction of longer span timber-only floor systems and have encouraged the development of timber-concrete composite (TCC) systems. The use of concrete would negatively impact on the carbon footprint of the TCC floor system and should be minimized. The purpose of this study was to study the impact on embodied carbon in the TCC system, when the ratio of timber and concrete was varied for specific floor spans. Two MTP products were considered, CLT and glued laminated timber (GLT). The floors were designed to satisfy structural, acoustic, and vibration criteria, and the results were presented in the form of span tables. It was found that using thicker MTP instead of adding concrete thickness to meet a specific span requirement can lead to lower embodied carbon values. Increasing concrete thickness for long-span floor systems led to a reduction in allowable floor span due to the vibration criterion being the controlling design parameter. Increasing timber thickness also resulted in higher strength and stiffness to weight ratios, which would contribute toward reducing the size of lateral load resisting systems and foundations, resulting in further reductions in the embodied carbon of the entire structure.

The Use of Machine Learning for the Prediction of fire Resistance of Composite Shallow Floor Systems

This paper is proposing an machine learning based expert system for preliminary prediction of the insulation fire resisting performance of shallow floor systems when subject to exposure to the ISO 834 Standard Fire Curve. The proposed system is a digital tool which incorporates a machine learning algorithm trained on the outcomes of pre-run two-dimensional finite element heat transfer analyses of shallow floor system details. The algorithm predicts the insulation performance of similar details with a measurable accuracy of 96% (i.e the insulation rating band was predicted correctly in 96% of the cases) without the requirement for an explicit deterministic analysis. The paper presents the challenges and prerequisites to build such an expert system and acts as a proof of concept for the use of machine learning for the assessment of the insulation performance of shallow floor system under the guidance of BS EN 1363-1:2012. A Support Vector Machine machine learning algorithm is adopted in this work. The required processes that were needed for the development of the expert system include the stages of data acquisition, exploratory data analysis, choice of machine learning algorithm, model training, tuning, and validation. This expert system is useful for practitioners to rapidly assess the feasibility of different construction details at early stages of the design process.

An analytical method to estimate temperature distribution of typical radiant floor cooling systems with internal heat radiation

Radiant floor cooling systems are increasingly used in practice. The temperature distribution on the floor surface and inside the floor structure, especially the minimum and average temperature of floor surface, determines the thermal performance of radiant floor systems. A good temperature distribution of the floor structure is very important to prevent occupant discomfort and avoid possible condensation in summer cooling. In this study, based on the heat transfer model of the single-layer homogeneous floor structure when there is no internal heat radiation in the room, this paper proposes a heat transfer model of single-layer floor radiant cooling systems when the room has internal heat radiation. Using separation variable methods, an analytical solution was developed to estimate temperature distribution of typical radiant floor cooling systems with internal heat radiation, which can be used to calculate the minimum temperature and the average temperature of typical composite floor structure. The analytical solution was validated by experiments. The values of the measured experiments are in a good agreement with the calculations. The absolute error between the calculated and the measured floor surface temperatures was within 0.45°C. The maximum relative error was within 2.31%. Prove that this model can be accepted. The proposed method can be utilized to calculate the cooling capacity of a typical multi-layer composite floor and will be developed in the future study for design of a typical radiant floor cooling system.

The Influence of Arch Flexibility On The Floor Deck Structural Characteristics For Composite Arch Steel Bridge

This paper presents an optimizing design for the floor deck for the composite arch steel bridge depending on the arch flexibility (the bridge’s main component). The design is based on second-order effects using nonlinear p-delta analysis. Many variables are considered in the parametric study, which is the arch’s in-plane flexibility, the out-of-plane flexibility of the arch, and the number and stiffness of the lateral bracing between the twin arches. The design has been done by graphical design software SAP2000 and based on AISC and AASHTO specifications. A numerical example is studded herein for the new proposed bridge of Batta in Al-Hilla city in Iraq which crossover Al-Hilla river for a width of 108m from bank to bank, the bridge has an overall width of 18 m including two lane-two way of 15.6 m width and walkways of 1.2 m on both sides. This study’s main objectives are the number and size of floor beams, deck thickness, and hence the overall weight of the bridge will be minimum, the goal of design is to select the lightest and most economical and practical composite floor decks. It has been concluded that the deflection decreases with the increase in the number of the floor beam, and the best result was the case of the distance between the floor beam is 1.95 m with a deflection of 71.95 mm, meaning that the flexibility is less as the number of floor beam increases. As for the change of the arch’s cross-section, the best result of the lesser girder deflection was in the case that the arch section with dimensions (0.8 x1.2x0.035) m. This indicates that the greater the moment of inertia, which leads to less deflection for cross over the main girder.

State of the art report on stub girder flooring systems

Stub girder flooring systems are a widely used system in modern steel buildings. This type of system is a composite flooring system consisting of a continuous steel beam and a reinforced concrete slab set apart by a series of short, and usually wide, flange parts known as stubs. While many studies and research have been conducted on this system in steel-concrete composite structures, comparable comprehensive research has not been done on Stub girder flooring system for timber construction. This study represents a review on stub girders, and focuses on experimental and analytical works in the area. Finally, pervious researches and experimental data about stub girder flooring system have been collected and summarized in a table format which has been listed parameters in the researches.

Ultimate flexural strength analysis of composite slim floor beam

This paper presents a new type of composite slim floor beam, determined by combining the results of an experimental study and theoretical analysis of the ultimate flexural strength of slim floor beams. The shear connectors play a significant role in the mechanical properties of this type of composite slim floor beam, because the precast concrete slab is laid on the bottom flange of the steel section and because the upper portion of the steel beam is encased in the cast-in-place concrete slab. To investigate the ultimate flexural strength, three specimens, which included headed studs, transverse steel bar shear connectors and no shear connectors, were tested. Additionally, a detailed numerical analysis was performed to verify the experimental results, which indicated that a higher-strength steel beam and thicker concrete slab can effectively enhance the stiffness and flexural capacity of the composite slim floor beam. Based on plastic mechanics and limit analysis theory, a calculation method was derived to estimate the ultimate flexural strength of a composite slim floor beam, and a comparison between the calculation and experimental results shows that the theoretical results exhibit good agreement with the experimental results, and the proposed analysis method can be used in future studies to gain a better understanding of the ultimate flexural strength of composite slim floor beams.

Analysis of the robustness of a steel frame structure with composite floors subject to multiple fire scenarios

This study presents robustness analyses of a three-dimensional multi-storey composite steel structure under the action of multiple fire scenarios. The main objective of the work is to improve current understanding of the collapse resistance of this type of building under different fire situations. A finite element approach was adopted with the model being firstly validated against previous studies available in the literature. The modelling approach was then used to investigate the collapse resistance of the structure for the various fire scenarios examined. Different sizes of fire compartment are considered in this study, starting from one bay, three bays and lastly the whole ground floor as the fire compartment. The investigation allows a fundamental understanding of load redistribution paths and member interactions when local failure occurs. It is concluded that the robustness of the focussed building in a fire is considerably affected by the size of fire compartments as well as fire location. The subject building can resist progressive collapse when the fire occurs only in the one-bay compartment. On the other hand, total collapse occurs when fire is located in the edge three-bay case. This shows that more than one fire scenario needs to be taken into consideration to ensure that a structure of this type can survive from collapse in the worst-case situation.

State of the art on composite cold‐formed steel flooring systems

AbstractThis article presents a comprehensive review of the state of the art in composite cold‐formed steel flooring research over the past couple of years. The most relevant and significant literature references were reviewed to provide some insights into trends and developments in composite cold‐formed steel floors. Advantages of this type of composite flooring system are also highlighted. A broad description of mainly two types of composite floor – mainly consisting of cold‐formed steel and concrete, and cold‐formed steel and timber‐based floorboards – are outlined in this study. The experimental and numerical investigations that have been carried out worldwide are likewise discussed in the paper. The most important aspects covered are shear connection behaviour and the flexural and dynamic behaviour of the floors. There is also a brief description of fire testing.

Performance of Ultra Shallow Floor Beams (USFB) exposed to standard and natural fires

This paper investigates computationally the fire performance of a plug steel-concrete composite flooring system, the partially encased ultra-shallow floor beams (USFB). The investigation of the behaviour of USFBs exposed to standard and natural fires is crucial in determining their fire resistance and evaluating their overall performance in contemporary construction. Although the product providers usually indicate the fire resistance of USFBs based on ΕΝ1994-1-2 procedures, the response to elevated temperature effects remains yet neither well documented nor clearly understood. This analysis involves two different beams of 5 m and 8 m span. Results show that the unprotected beams experience severe temperature gradients while exposed to standard fire, as the lower flange still remains unprotected in contrast to the upper steel parts of the cross-section which are encased in concrete. Their fire resistance rating is found approximately at 40 min. Moreover, different thermal gradients are developed when the USFBs are exposed to natural fires (slow and fast burning). When the lower flange is protected with intumescent coatings, the USFBs have shown increased fire resistance and they can survive a full duration of a natural fire under realistic utilization ratios. From the parametric analyses, the optimized thicknesses for the required intumescent coating were obtained to achieve 60, 90, and 120 min of fire resistance and for surviving of natural fires exposures.

Distributed fiber optic measurements of strain and temperature in long-span composite floor beams with simple shear connections subject to compartment fires

This study explores an instrumentation strategy using distributed fiber optic sensors to measure strain and temperature through the concrete volume in large-scale structures. Single-mode optical fibers were deployed in three 12.8 m long steel and concrete composite floor specimens tested under mechanical or combined mechanical and fire loading. The concrete slab in each specimen was instrumented with five strain and temperature fiber optic sensors along the centerline of the slab to determine the variation of the measurands through the depth of the concrete. Two additional fiber optic temperature sensors were arranged in a zigzag pattern at mid-depth in the concrete to map the horizontal spatial temperature distribution across each slab. Pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA) was used to determine strains and temperatures at thousands of locations at time intervals of a few minutes. Comparisons with co-located strain gauges and theoretical calculations indicate good agreement in overall spatial distribution along the length of the beam tested at ambient temperature, while the fiber optic sensors additionally capture strain fluctuations associated with local geometric variations in the specimen. Strain measurements with the distributed fiber optic sensors at elevated temperatures were unsuccessful. Comparisons with co-located thermocouples show that while the increased spatial resolution provides new insights about temperature phenomena, challenges for local temperature measurements were encountered during this first attempt at application to large-scale specimens.

Numerical parametric study on steel-concrete composite floor beams vibrations due to pedestrian traffic

Human perception of floor vibrations and uncompromised serviceability of equipment are two most important acceptability criteria considering floor vibrations. While verification of deflection is a simple and well-known procedure in structures' design for serviceability limit state, the fulfilment of floor vibrations acceptability criteria are presented in different standards in the form of various calculation procedures. Results achieved through those calculation procedures are presented in the form of various classification of floor structures. Classification of composite floor structures due to vibrations is inconsistent considering different calculation procedures. Comparison of various calculation procedures for the definition of composite floor vibrations is presented in this paper. In addition, a parametric analysis is performed on the wide range of steel-concrete composite floor structures, through analysis of various composite floor layouts and a wide range of imposed loads values. The analysis of the relation between deflection, vertical vibrations and accelerations of steel-concrete composite floor beams is presented in this paper. The results of the parametric analysis are given through direct relation between deflections of composite beams and achieved floor class for the fulfilment of vibrations acceptability criteria due to the pedestrian walking.

Experimental evaluation of induced human walking vibrations on steel-concrete composite floors

abstract: This work presents the experimental evaluation of the dynamic behavior of Steel and concrete composite floors, from a human comfort point of view, when submitted to human walking. The structural model investigated was a real composite floor system under construction, with a total area of approximately 1300 m2. A preliminary numerical model was developed in order to guide the ideal positioning of excitation and instrumentation to be adopted in the experimental “in situ” evaluation. Next, free vibration tests were carried out to obtain the modal parameters of the structure. More than 180 forced vibration tests with excitation caused by a person walking at different step frequencies and directions were performed to determine de maximum structure’s response. The results found were compared with human comfort criteria recommended by national and international standards and design guides. Subsequently, a people quantity influence analysis on the dynamic response of the floor was carried out, where it was noticed that the increase in the number of users walking on the floor also increased the peak acceleration value. This fact emphasizes the need to carry out experimental evaluations considering the variation of people quantity on floor activity in order to evaluate the real scenario of human vibrations induced in the structure under service.

Experimental studies on vibration serviceability of composite steel-bar truss slab with steel girder under human activities

In this study, the vibration serviceability of a composite steel-bar truss slab with steel girder system considering the human-structure interaction was investigated systematically through the on-site testing. Impulse excitations (heel-drop and jumping) and steady-state motions (walking and running) were performed to capture the primary vibration parameters (natural frequency, model shape, and damping ratio) and the distribution of peak accelerations. The composite floor possesses a low frequency of approximately 7.90 Hz and the damping ratio of ≈ 2.10%. The walking and running excitations by one person (single excitations) were considered to evaluate the vibration serviceability of the composite floor. The measured accelerations show a satisfactory vibration perceptibility. For design convenience and safety, a crest factor B rp (the ratio of peak acceleration to root-mean-square acceleration induced from an excitation) is proposed. Comparisons of the modal parameters determined from the tests (walking, running, heel-drop, and jumping) reveal there is an interaction exists between the human excitation and the composite floor. This interaction effect reduces the damping ratio of the composite floor.

Assessment of design codes for the in-service behaviour of steel-concrete composite slabs

Abstract Steel-concrete composite slabs, also known as steel decking floor slabs or popularly as steel decks® have recent development and are advancing in Brazilian construction. There are relatively few researches about the long-term effects on composite slabs, and it has been identified that they can be significant in the evolution of deflections, mainly due to the effects of non-uniform shrinkage. However, there are no Brazilian references on the subject and Brazilian Code ABNT NBR 8800:2008 does not indicate any procedure for its evaluation. This paper presents a study on the serviceability limit state of excessive deflection with the application of two simplified approaches: Eurocode 4:2004 (European code) and AS/NZS 2327:2017 (Australian code), also comparing them against experimental results by the authors and literature. Due to the impermeability of the soffit face promoted by the steel decking, the occurrence of non-uniform shrinkage is a relevant aspect. As a consequence, the deflections were underestimated by Eurocode 4. At the same time, the simplified approach of AS/NZS 2327, which explicitly takes into account the non-uniform shrinkage, presented good accuracy when compared to the experimental values. Finally, authors indicate the use of more robust prediction models for the evaluation of deflections in composite floors.