Search

Increasing the speed of high-speed trains requires the lightweight design of vehicles to meet the economic and ecological efficiency requirements of such trains. However, these objectives conflict with the interior noise control in high-speed trains because the sound insulation of panel structures follows the mass law principle. The train floor, the main train body structure of the high-speed train, is vital for interior noise control because its sound insulation performance directly affects the interior noise levels. Owing to the complexity of the composite floor system, reliable measurement and accurate estimation of its sound insulation performance are often time-consuming and laborious. To address this situation, this study proposes an artificial neural network (ANN)-based model to predict the sound insulation characteristics of a composite floor. First, a sound insulation model of the composite floor is built based on statistical energy analysis (SEA). The sound insulation performance of 200 cases of composite floors is calculated by varying the dimensions of the extruded floor, thickness of the webs, sound-absorbing material, and wooden floor to formulate a sound insulation database of composite floors. Next, an ANN model is introduced and trained on the sound insulation database. The sound insulation prediction results obtained using the ANN model are compared to the prediction results obtained using the experiment to validate its effectiveness. Subsequently, the NSGA-II optimization method is used to optimize the sound insulation structure of the composite floor. Compared with the regular composite floor structure, the optimized structure reduced the mass of the composite floor by 10.93 kg and increased the weight of the sound insulation (Rw) by 6.3 dB. The proposed method can be an effective, economical, and efficient tool for vehicle designers and can help promote the sound insulation optimization design of high-speed train composite floors. [ABSTRACT FROM AUTHOR]

Copyright of Automobile Technology is the property of Automobile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Filler agglomeration, single filler type, poor filler-matrix compatibility, and lack of toughness are the main problems that restrict the development of the polyvinyl chloride (PVC) manufacturing industry. In this work, PVC composites were prepared with silica micropowder (SMP) as a filler. Titanate coupling agent (TCA-KTTO) modification and chlorinated polyethylene (CPE) toughening treatment were utilized to enhance the composites performance. Herein, we successfully obtained SMP/PVC composites with high strength, high toughness, and outstanding heat resistance. The optimal dosage of titanate coupling agent for SMP surface modification was determined to be 1.5 wt% by mechanical and thermal conductivity tests. With an increase in the filling content of modified silica micropowder (mSMP), the density, surface hardness, Young's modulus, flexural modulus, thermal conductivity, and thermal stability of mSMP/PVC composites were significantly improved. The notched impact strength of mSMP/PVC composites shows a significant increase with the addition of CPE. At a CPE dosage of 7.5 parts per hundred parts of resin (phr), the notched impact strength of mSMP/PVC composites was enhanced by 59.15%, and the glass transition temperature was improved by 6.1 °C. The co-extruded hollow flooring, fabricated by the SMP reinforced PVC composites, meets Chinese standard GB/T 24508-2020, which has a wide range of applications in panels and profiles, such as seaside boardwalks and outdoor parks.

As a new green material, steel-paper straw board (PSB) composite structures are widely used in practical engineering. This study proposed a new cold-formed thin-walled C-shaped steel-paper straw board (CFCSPSB) composite floor. To study its mechanical properties, flexural experiments were conducted on three composite floors. The experimental results showed that the combined effect of PSB and cold-formed thin-walled C-shaped steel (CFCS) beam was good, and the local buckling caused by the restraint effect of PSB on the CFCS beam was an important factor for the failure of the composite floor. On this basis, the composite floor was investigated by finite element analysis (FEA) software ANSYS, and the FEA results were consistent with the experimental results. Then, the effect of different factors on the flexural capacity of the composite floor was analysed by ANSYS. The obtained results showed that reducing the screw spacing and floor span, or increasing the CFCS beam cross-sectional size, web height of CFCS beam, and CFCS thickness could improve the flexural capacity of composite floors, and the calculation formula of flexural capacity for the composite floor was proposed.

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: This research proposes an equivalent calculation method for vibration analysis of composite floor slab is proposed to effectively analyze the vibration of the profiled steel sheet-concrete composite floor (PSSCCF) prefabricated structure caused by high-speed trains. Methods: For this purpose, an equivalent calculation model of PSSCCF was established, and the railway environment vibration of the PSSCCF equivalent calculation model was verified through experiments. Besides, a finite element model of the track-subgrade-soil-prefabricated structure was established, and the influence of speed, axle load, and the soil properties on the railway environmental vibration of PSSCCF prefabricated structure was analyzed and compared. Also, the railway environmental vibration difference between PSSCCF and the cast-in-place reinforced concrete floor (CRCF) was analyzed. Results: The results indicate that the equivalent analysis method of composite floor slab proposed can effectively predict the environmental vibration caused by high-speed trains. [ABSTRACT FROM AUTHOR]

Desert sand foamed concrete (DSFC), which offers advantages, such as fire resistance, sound insulation, construction convenience, and environmental benefits, has not been used in cold-formed steel (CFS) composite floors. In this study, four full-scale specimens were designed and tested under four-point bending to investigate the effect of foamed concrete filling and holes. The load–deflection curves and strain distribution at mid-span were measured and analyzed. The experimental results indicated that the failure modes of the CFS composite floors were local buckling at the top flange for specimens without holes and tensile failure at the bottom flange for specimens with holes, respectively, which differed from the web crippling observed in non-composite floors. Moreover, due to the presence of foamed concrete, the flexural stiffness was significantly improved by 117.6% and 73.6% for the specimens without holes and with holes, respectively, while ultimate capacity increased by 224.9% and 121.8%, respectively. Through the nonlinear finite element models validated against experimental results, it was found that the flexural behavior was improved with the increase in CFS thickness and foamed concrete strength. The impact of the holes was not obvious for specimens infilled with holes. [ABSTRACT FROM AUTHOR]

In order to study the bending resistance performance of the cold-formed thin-walled steel-oriented strand board(OSB) two-way slab composite floor. A full-scale composite floor test piece was designed and manufactured, and a monotonic static stacking test was performed on it under the condition of simply supported on four sides. The nonlinear finite element analysis model of the coldformed thin-walled steel-OSB slab composite floor was established. On this basis, by changing the height of the OSB beam web, the thickness of the cold-formed thin-walled steel plate and the screw spacing, the influence of each parameter on the mechanical performance of the composite floor was analyzed. The experimental results show that OSB plate and cold-formed thin-walled steel can work well together and coordinate deformation. The load-deflection(P-Δ) curve of the composite load-bearing beam in the x and y directions of the specimen is basically the same. As the height of the beam web and the thickness of the steel plate increase, the flexural bearing capacity of the composite floor is significantly increased. The end structure of cold-formed thin-walled steel at the bottom of the beam and the OSB web can effectively reduce the slip deformation of the steel-timber contact section. It is concluded that the combined floor has good bidirectional force performance. Increasing the height of the beam web, increasing the thickness of the steel plate and appropriately reducing the screw spacing can improve the bearing capacity of the floor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nanchang University (Engineering & Technology) is the property of Nanchang University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the increasing speed of high-speed train, it is more and more difficult to reduce the vibration and noise inside the train. The floor of the train, as a carriage component in direct contact with passengers, is of great significance to improve its vibration and sound isolation performance to ensure the comfort of passengers. In this article, a floor vibration isolator with quasi-zero stiffness is designed based on the dimensional parameters of the traditional floor vibration isolator, and the vibration isolation performance is analyzed by the finite element model of the floor vibration isolator from the static and dynamics aspects, respectively. The load-displacement curves of the floor vibration isolator are obtained through static simulation calculations, and the dynamic analysis of the floor vibration isolator is carried out by simulation methods, which verifies the low-frequency vibration isolation performance of the floor vibration isolator under different working conditions, and the vibration isolator has a good prospect for development., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

This paper summarizes the findings of two full-scale blasts tests on a steel braced frame structure with composite floor slabs, which are representative of a typical office building. The aim of this research study was to experimentally characterize the behavior of conventionally designed steel braced frames to blast loads when enclosed with conventional and blast-resistant façade. The two tests involved a three-story, steel braced frame with concentrical steel braces, which are designed to resist typical gravity and wind loads without design provisions for blast or earthquake loads. During the first blast test, the structure was enclosed with a typical, non-blast-resistant, curtainwall façade, and the steel frame sustained minimal damage. For the second blast test, the structure was enclosed with a blast-resistant façade, which resulted in higher damage levels with some brace connections rupturing, but the building did not collapse. Observations from the test program indicate the appreciable reserved capacity of steel brace frame structures to resist blast loads.

Vibration performance of a one-way simply supported timber-concrete composite (TCC) floor section has been studied using analytical as well as numerical methods. Focal points have been verification and validation of results from analytical and numerical calculations of vibration response based on experimental data. For the analytical calculations, floor bending stiffness and vibrational response are determined from methods proposed in the current and revised versions of Eurocode 5. The numerical calculations based on the finite element (FE) method are done using 3D solid elements with orthotropic material parameters. When comparing the results of the FE analysis, better agreement with the experimental data is reached for the fundamental frequency when 3D solid elements are used rather than 3D beam elements. Furthermore, better agreement with the experimental data is reached for RMS acceleration by FE analysis rather than the method based on Eurocode 5. For detailed analysis, the authors suggest performing dynamic FE analysis and calculating vibration response from the TCC floor's modal responses as eigenmodes and natural eigenfrequencies below 40 Hz. For future studies, it is recommended that the verification of vibration response may be accomplished by applying standard EN 16929. [ABSTRACT FROM AUTHOR]

Abstract A two-dimensional interface finite element capable of associating flat shell elements positioned one above the other was developed. The implemented interface element can physically simulate the contact between the flat shell elements and connect the reference planes of the shell elements above and below it. The formulation presented allows consideration of nonlinear behavior for the deformable connection as well as for the concrete and steel materials that make up the shell structure. One of the practical applications analyzed in this research is the numerical simulation of composite floors formed by a reinforced concrete slab connected to steel beams through a deformable connection. In this case, the concrete slab and the steel beams are discretized by flat shell elements and the deformable connection is discretized by two-dimensional interface elements. Experimental and numerical results from literature were used to validate the implemented elements. In the two examples analyzed, the results obtained for the displacements were close, with the difference, in the first case, being associated with uncertainties during the experimental test and in the second, the difference in theories used in the formulation of the implemented elements.

Desert sand foamed concrete (DSFC), which offers advantages, such as fire resistance, sound insulation, construction convenience, and environmental benefits, has not been used in cold-formed steel (CFS) composite floors. In this study, four full-scale specimens were designed and tested under four-point bending to investigate the effect of foamed concrete filling and holes. The load–deflection curves and strain distribution at mid-span were measured and analyzed. The experimental results indicated that the failure modes of the CFS composite floors were local buckling at the top flange for specimens without holes and tensile failure at the bottom flange for specimens with holes, respectively, which differed from the web crippling observed in non-composite floors. Moreover, due to the presence of foamed concrete, the flexural stiffness was significantly improved by 117.6% and 73.6% for the specimens without holes and with holes, respectively, while ultimate capacity increased by 224.9% and 121.8%, respectively. Through the nonlinear finite element models validated against experimental results, it was found that the flexural behavior was improved with the increase in CFS thickness and foamed concrete strength. The impact of the holes was not obvious for specimens infilled with holes.

This study aims to present a multi-criteria decision analysis (MCDA) for comprehensive performance evaluation of the alternative design of timber–concrete composite (TCC) floor system. Considered objectives are serviceability and sustainability performance with associated criterion as (1) comfort class regarding springiness and vibrations, (2) architectural quality with associated criterion as open spaces, (3) environmental aspect with associated criterion as CO2 emissions and (4) cost aspect with associated criterion as the total costs. Analytical Hierarchy Process (AHP) and Complex Proportional Assessment (COPRAS) as the methods in the multi-criteria analysis have been combined for (1) determining the weighting of criteria based on the survey results, (2) verifying the consistency ratio of decision matrix made by experts and (3) for ranking and selecting the optimal concept design among design candidates. According to the results, the TCC floor with the span length of 7.3 m belonging to comfort class A has got the highest ranking. However, sensitivity analysis indicates that the TCC floor with a 9.0 m span length belonging to comfort class A shall be selected as the optimal concept design. The study contributes by developing a complete concept design tool for TCC floor systems using AHP combined COPRAS methods to handle both beneficial and non-beneficial criteria. [ABSTRACT FROM AUTHOR]

A two-dimensional interface finite element capable of associating flat shell elements positioned one above the other was developed. The implemented interface element can physically simulate the contact between the flat shell elements and connect the reference planes of the shell elements above and below it. The formulation presented allows consideration of nonlinear behavior for the deformable connection as well as for the concrete and steel materials that make up the shell structure. One of the practical applications analyzed in this research is the numerical simulation of composite floors formed by a reinforced concrete slab connected to steel beams through a de- formable connection. In this case, the concrete slab and the steel beams are discretized by flat shell elements and the deformable connection is discretized by two-dimensional interface elements. Experimental and numerical results from literature were used to validate the implemented elements. In the two examples analyzed, the results obtained for the displacements were close, with the difference, in the first case, being associated with uncertainties during the experimental test and in the second, the difference in theories used in the formulation of the implemented elements. [ABSTRACT FROM AUTHOR]

Characterizing structural resiliency after severe damage to a few load-carrying members is challenging. Engineers use various computational approaches to assess the vulnerability of structures and to evaluate the parameters that affect their response. Few of these approaches are capable of predicting the actual peak load-carrying capacity a damaged structure can withstand before experiencing total collapse, and practically none of them have been verified against actual test results. In this paper, experimental data from large-scale tests on steel–concrete composite floor systems under different column loss scenarios were used to develop and to validate a high-fidelity numerical modeling approach capable of predicting the response of the tests up to total collapse. This approach incorporates geometric and material nonlinearity, explicit modeling of steel and concrete failure, and contact modeling using LS-DYNA version R10.2.0. Nearly all specimen components were modeled using brick elements, including the concrete slab, steel members, bolts, and other connecting elements. The corrugated metal decking was represented with shell elements, and beam elements represent the reinforcing steel and shear studs. The predicted response and ultimate load–carrying capacity up to total collapse show good agreement with the results of the experimental tests. Validating the numerical models revealed the sensitivity of various modeling parameters and demonstrated the potential for inaccurate predictions of response when certain parameters were not correctly specified. The most important of these parameters are described in this manuscript. Lessons learned from the current study are helpful for understanding the mechanisms that have the greatest impact on collapse of composite floor systems, and these lessons can be used to gain insight on the collapse potential of other structures with different geometries or configurations. [ABSTRACT FROM AUTHOR]

This paper proposes a novel multi-cavity steel–concrete composite floor. The mechanical properties of multi-cavity steel–concrete composite floor were studied by static load test. Based on full-scale tests on 2500 × 1000 × 120 mm multi-cavity steel–concrete composite floors, the bearing capacity and failure characteristics of the composite floor were analyzed. Compared with the existing prefabricated floor, the reliability of the test was verified by finite element simulation. The influence of steel plate material thickness, floor thickness, cavity size and span on the mechanical properties of composite floor was analyzed. The results showed that the composite floor had stronger bearing capacity and better ductility and integrity than the existing precast floor. The bearing capacity and stiffness of composite floor were positively correlated with the thickness of steel plate and floor, and negatively correlated with the cavity size and span. [ABSTRACT FROM AUTHOR]

The vibration of lightweight floors under service loads may cause annoyance to the occupants of buildings, particularly when the fundamental natural frequency of the floor is close to the range of frequencies 4–8 Hz to which the human body is sensitive. Accordingly, the vibration response of the floors is a governing factor in the structural design of steel-timber composite (STC) flooring systems, which have been proposed as an innovative alternative to conventional steel-concrete floors. The current study is part-2 of a comprehensive experimental and numerical study on serviceability performance of the STC floors under human-induced excitations. Natural frequencies are often used as measure of the acceptable vibration performance of the floors. Accordingly, the finite-element (FE) models calibrated and validated against the experimental results in part-1 are used to predict the natural frequencies of the typical STC floors with medium to long spans, and the effect of the geometry of the floor, the mechanical properties of the connections and the magnitude of superimposed loads on the natural frequencies of the STC floors are investigated through a paramtric study. In addition, dynamic analyses are carried out to predict the vibration response (i.e. displacements, velocities and accelerations) of the STC floors, developed in the parametric study, subject to human activities and the vibration performance of the floors with respect to acceptability criteria derived from various building codes is assessed. Lastly, some floor design recommendations are made to ensure satisfactory performance of the STC floors under human-induced vibrations according to the existing building codes. • Mode shapes and frequencies of STC floor were studied by finite element simulation. • Parametric study was performed on influential variables of STC floors vibration. • Floors vibration indices were compared with existing building provisions. • A design method for vibration of STC was proposed based on floors' OS-RMS 90 value. [ABSTRACT FROM AUTHOR]

Highlights • Various parametric effects on load-resisting mechanisms of 3D composite floor systems under an internal column removal scenario are investigated by FE simulations. • Effects of slab aspect ratio and joint type on robustness of 3D composite floor systems are assessed by an analytical model. • A few joint combinations are recommended for building robust composite floor systems against column removal scenario. • Consistency between the FE simulations and the analytical predictions is confirmed through a comparison of energy stored in different structural members. Abstract This paper presents parametric studies on three-dimensional steel-frame-composite-floor systems (3D composite floor systems) subjected to column loss using macro-based finite element (FE) models and a verified analytical method. The FE modelling method is verified by four actual experimental tests with three important variables, viz. slab aspect ratio, boundary condition and degree of composite action between composite slabs and steel beams. To overcome the shortage of data acquisition in the actual composite floor system tests, the FE models can be used to investigate the effects of these variables on load-resisting mechanisms, such as flexure and catenary action in the double-span girder and the double-span beam over the missing column, and flexure and tensile membrane action in composite slabs. In addition, the parametric studies are extended to include slab thickness. In a similar manner, the analytical model is used to study the effects of slab aspect ratio and joint type on robustness of 3D composite floor systems. After evaluating the robustness of eight sub-structures with different combinations of extended-end-plate, flush-end-plate, web-cleat and fin-plate joints, a few combinations are recommended. Lastly, consistency between FE simulations and the analytical predictions is confirmed through a comparison of energy stored in different structural members. [ABSTRACT FROM AUTHOR]

Because floors play an important role in buildings, it is of great significance to study the residual bearing capacity of floors after fire for effectively guiding the repair and performance evaluation. Static load tests of the post-fire bearing capacity of three composite floors of lightweight aggregate concrete and thin walled steel beam after exposure to the fire with a maximum temperature of 700°C and a duration of 90 min were completed. The test results show that although the concrete of composite slab specimens has been seriously cracked, the skeleton beams have obviously buckled and deformed after fire, and the maximum residual vertical displacement of the whole slab has reached L/80 (Lis span of floor), the composite slab specimens still have a high residual bearing capacity: the ultimate load of static load test is 4.12 kN/m² and the maximum deflection of center point is 17.88 mm (L/112), while no overall collapse is observed. It is further concluded that the two-way composite floor specimens with the ordinary nails for resisting shear and steel bars for joining the concrete panels perform better in terms of bearing capacity and stiffness than that with the U-type shearing keys and steel plates. It is seen that although the use of cement mortar as post pouring layer of the composite slabs may have a more obvious effect on improving the post-fire mechanical property of the composite slabs than the use of ceramsite concrete, it is still feasible for the ceramsite concrete to be used as the post pouring layer of the slabs in consideration of decreasing weight of the slabs. It is also shown that the ceramsite concrete may meet the fundamental requirement for bearing capacity and stiffness of the slabs. [ABSTRACT FROM AUTHOR]

Abstract Studies of steel-timber composite (STC) connections and STC beams under sagging bending have been reported elsewhere in the literature using push-out and four-point bending tests respectively. However, the structural behaviour of STC beam-to-column connections under hogging bending moments (with the prefabricated timber slabs in tension) have hitherto not been investigated. In particular, the connection between the two prefabricated timber slab panels (across the column) has a major influence on the structural performance of a STC beam-to-column connection and is the focus of the current study. Eight full-scale STC beam to steel column cruciform specimens with different connections (half lap, single and double surface spline with timber and/or steel plate) for the timber slabs were fabricated and tested under a monotonically increasing downwards displacement, and these are described in this paper. The bending moment capacity, rotation capacity, failure mode, stiffness and ductility of the STC connections are evaluated and discussed. The composite steel-timber system exhibits both appreciable ductility and rotation capacity which fulfil the existing design requirements for semi-rigid composite connections in Eurocodes EC3 and EC4. Furthermore, the negative bending moment capacity of STC connections is significantly higher than that of bare steel connections without a timber slab. Highlights • Study structural behaviour of semi-rigid steel-timber composite (STC) connections • Conduct experiments on STC beam to column connections with flush end plate • Demonstrate hogging bending moment and rotation capacity of the STC connections • Effect of timber-to-timber slab connection on the behaviour of STC connections [ABSTRACT FROM AUTHOR]

The delamination of concrete from steel decking will reduce the strength and decrease the stiffness of the composite slab. Visual monitoring of delamination is typically not possible in many cases. A possible alternative is ultrasonic-based health monitoring. In this study, a novel damage index (DI) based on the absolute energy change (AEC) of the ultrasonic waves is adopted to quantify delamination damage in the composite floor. AEC-DI was constructed based on the decomposed signals provided by the wavelet transform. The monitoring process of the composite floor was conducted ultrasonically under flexural loading. An ultrasonic surface (Rayleigh) wave is employed for damage detection using gel-coupled piezoceramic sensors. The results revealed that the reliability and accuracy of AEC-DI in detecting composite floor separation is better than that of RMSD-DI. [ABSTRACT FROM AUTHOR]

This paper proposes a novel multi-cavity steel–concrete composite floor. The mechanical properties of multi-cavity steel–concrete composite floor were studied by static load test. Based on full-scale tests on 2500 × 1000 × 120 mm multi-cavity steel–concrete composite floors, the bearing capacity and failure characteristics of the composite floor were analyzed. Compared with the existing prefabricated floor, the reliability of the test was verified by finite element simulation. The influence of steel plate material thickness, floor thickness, cavity size and span on the mechanical properties of composite floor was analyzed. The results showed that the composite floor had stronger bearing capacity and better ductility and integrity than the existing precast floor. The bearing capacity and stiffness of composite floor were positively correlated with the thickness of steel plate and floor, and negatively correlated with the cavity size and span.

Highlights • A model is proposed to estimate the responses of composite floors under internal column loss. • The model can accurately predict push-down load–displacement curves. • The model can capture the effects of key parameters. • The procedure of the model can be implemented by a spreadsheet method. Abstract This is the first time that a mechanical model is proposed to estimate the entire load–deflection response of three-dimensional (3D) steel-frame-composite-slab systems (composite floors) subjected to internal column loss. The model incorporates three branches to capture the response at small deformation, transitional and large deformation stages. For ease of hand calculations, the load carried by a 3D composite floor is assumed to be the summation of the respective contributions from the composite slabs and the steel sub-frame. At small deformation stage, the load is resisted through flexural action. But at large deformation stage, structural capacity is mostly contributed by membrane action in the slabs and catenary action in the steel beams. The assumptions and failure criteria in the last stage are based on the results of actual experimental tests. The derivations are discussed in detail, followed by verifications of the model. Compared with actual test results and numerical simulations, the model shows reasonable accuracy in predicting load–displacement curves of 3D composite floor systems under an internal column removal scenario. Besides this novelty and distinct feature from other studies, the model can capture the effects of key parameters, such as slab aspect ratio, joint type, number of joint bolts, slab thickness, reinforcement ratio in the slab and thickness of steel decking. Most importantly, the procedure of the model can be implemented by a spreadsheet method, which provides a simple and numerical robust tool for engineers to calculate progressive collapse resistance of structures for a missing column scenario. [ABSTRACT FROM AUTHOR]

Highlights • A newly developed polymeric material was applied to a steel-polymer hybrid floor panel. • The hybrid panel exhibited very ductile and stable behavior maintaining its structural integrity. • The bond strength of polymer was sufficient to resist the forces generated between steel and polymer. • Design equations for predicting flexural strength and stiffness of the proposed panel were established. • The experimentally-validated cutting and joining methods for field applications were also presented. Abstract A new floor system for steel buildings was developed that can replace conventional concrete deck slab systems. The floor system is designed with a new type of composite panel with a polymeric material filling between the top and bottom steel plates. Its salient features are its light weight and simple installation that reduce structural materials and shorten the construction period. Experiments with various independent variables were performed to evaluate the flexural capacity of the proposed composite panel, and a finite element analysis was also conducted to examine the state of the stresses generated between the steel plate and the polymeric core. The test results showed that the proposed panel exhibited very ductile behavior and maintained its structural integrity even after a maximum load. No other failure mode than the face yielding of the top and bottom steel plates was observed. The bond strength between the polymeric material and the steel plates was confirmed to be sufficient, even without any special surface treatment or any additional shear connectors, to maintain the stability of the proposed panel and to resist the forces generated at the interface between the two materials. Design equations for predicting the flexural strength and stiffness of the proposed panel were proposed, and its suitability was verified. Additionally, the experimentally tested efficient methods for field applications of the proposed panel regarding cutting and joining were presented in this paper. [ABSTRACT FROM AUTHOR]

This paper presents probabilistic capacity models for composite floor systems subjected to column loss. The probabilistic capacity models are formulated by adding explanatory terms to an existing deterministic model. The explanatory terms are selected to correct the bias in deterministic capacity model. After that, virtual experiment data generated from finite element simulations are used to calibrate the model parameters. The finite element models consider the effect of axial loading on steel connection and the slab membrane action. The calibration of model parameters is conducted using the Bayesian inference approach. As an application and validation of the probabilistic capacity models, fragility analyses of typical composite floor systems are carried out. The developed fragility curves are compared with those from finite element analysis cooperated with Monte Carlo simulation. The comparison results show that the proposed capacity models are considered reasonable in predicting the resistance capacity of the composite floor and seek a compromise between model accuracy and computational efficiency. The proposed capacity models can be used to carry out a rapid fragility analysis against progressive collapse. [ABSTRACT FROM AUTHOR]

In order to research the in-plane hysteretie behavior of cold-formed steel floor, in-plane cyclic loading tests of three full scale models of cold-formed thin-walled steel composite floors with different patterns of floor panel were earned out. The three models were profiled steel sheet composite floor, profiled steel sheet-gypsum based self-leveling mortar composite floor and profiled steel sheet-gypsum based self-leveling mortar composite floor with wire mesh. The failure mode, hearing capacity and ductility as well as bond behavior of floors were investigated. Experimental results show that the failure mode of specimen is the shear failure of the self-drilling screws connecting corrugated metal deck to end joists. Only minor damages occur to the gypsum based self-leveling mortar floor panel and middle CFS joists. The three floor specimens show good in-plane mechanical behavior in terms of hearing capacity, stiffness, energy dissipation and ductility. The overall working performance of the cold-formed thin-walled steel-gypsum based self-leveling mortar composite floor is exceptional. The application of wire mesh can improve the in-plane stiffness, bonding properties and crack resistance of composite slabs. However, it has negative influence on ductility of floor. [ABSTRACT FROM AUTHOR]

In this paper, three-dimensional steel frame-composite slab systems (3-D composite floor systems) are simulated by verified macro-based models to investigate the structural performance under internal column removal scenarios. The authors have studied the load-transfer mechanisms of 3-D composite floor systems under internal column-removal scenarios, such as flexural action, compressive arch action, tensile membrane action and catenary action, and the final failure mode. In addition, both displacement-based and force-based dynamic increase factors ( DIF s) are obtained and their applicability for predicting progressive collapse resistance is discussed. Moreover, the force-based increase factor ( DIF p ) for 3-D composite floor systems are compared with those for 2-D steel frames and also compared with the values calculated based on DoD design guide. Based on dynamic analyses, several conclusions are found. Firstly, the dynamic ultimate state does not correspond to the static ultimate state in terms of load and deformation. Secondly, the energy method can predict the maximum dynamic responses well but it does not give the failure mode for the dynamic ultimate limit state. Lastly, comparing a 3-D composite floor system with the corresponding 2-D steel frame system, the former requires more ductility, and the DIF p for the 3-D composite floor system is smaller than that for the 2-D steel frame. [ABSTRACT FROM AUTHOR]

This paper concerns the short-term behaviour of innovative steel-timber composite (STC) floors comprising of cross-laminated timber panels connected to steel girders by various mechanical fasteners and/or glue. The results of four-point bending tests performed on full-scale STC beams are reported and the structural behaviour (the load-deflection response, short-term stiffness, peak load capacity, and failure modes) of the proposed STC system is studied. In addition, extensive non-linear 1D and 2D finite element (FE) analyses of STC beams are carried out and the numerical results are verified against the test results. It is shown that 1D and 2D FE models are adequate in capturing the structural response of the STC beams. Using the FE and experimental results, the composite efficiency of STC beams that can significantly influence their structural behaviour beams is determined and reported in the paper. [ABSTRACT FROM AUTHOR]

This paper presents experimental investigations on the thermal and mechanical behavior of composite floors subjected to ISO standard fire. Four 5.2 m×3.7 m composite slabs are tested with different combinations of the presence of one unprotected secondary beam, direction of ribs, and location of the reinforcement. The experimental results show that the highest temperature in the reinforcements occurs during the cooling phase (30–50 °C increment after 10-min cooling). The temperature at the unexposed side of the slabs is below 100 °C up to 100-min heating, compared to the predicted fire resistance close to 90 mins from EC4. For the slabs without secondary beams, the cracks first occur around the boundaries of the slab, while for the slabs supported by one unprotected secondary beam, concrete cracks first occur on the top of the slab above the beam due to the negative bending moment, and later on develop around boundaries. Debonding is observed between the steel deck and concrete slab. The secondary beam significantly impacts the deformation shape of tested slabs. Although a large deflection, 1/20 of the span length, is reached in the tests, the composite slabs can still provide sufficient load-bearing capacity due to membrane action. The occurrence of tensile membrane action is confirmed by the measured tensile stress in the reinforcement and compressive stress in the concrete. A comparison between measured and predicted fire resistance of the slabs indicates that EC4 calculations might be used for the composite slabs beyond the specified geometry limit, and the prediction is conservative. [ABSTRACT FROM AUTHOR]

A new composite floor system was developed to reduce floor-to-floor height and to improve structural capacity and fire resistance as compared with existing encased composite floor systems. The proposed system is composed of asymmetric steel beams with web openings, a biaxial hollow concrete slab, and glass fiber-reinforced plastic (GFRP) plates. The shear resistance of the typical composite beams is commonly determined based on the shear strength of the steel web alone. However, for the proposed system, because the steel web has several circular openings, the concrete contribution to the shear resistance should be included in the design equation. In this paper, tests and finiteelement analyses were conducted to evaluate the contribution of the shear-resisting components in the proposed system. An asymmetric steel beam with web openings, inner concrete panels, and a biaxial hollow concrete slab within the effective width for shear were considered as shear-resisting components. Each component fully resisted the applied shear force, exceeding the expected value until failure, and the design equation suggested was suitable for predicting the shear strength of the proposed system. [ABSTRACT FROM AUTHOR]

Over the past decade, much research has focused on the behaviour of structures following the failure of a key structural component. Particular attention has been given to sudden column loss, though questions remain as to whether this event-independent scenario is relevant to actual extreme events such as explosion. Few studies have been conducted to assess the performance of floor slabs above a failed column, and the computational tools used have not been validated against experimental results. The research program presented in this paper investigates the adequacy of sudden column loss as an idealisation of local damage caused by realistic explosion events, and extends prior work by combining the development of accurate computational models with large-scale testing of a typical floor system in a prototypical steel-framed structure. The floor system consists of corrugated decking topped by a lightly reinforced concrete slab that is connected to the floor beams through shear studs. The design is consistent with typical building practices in the US. The first test has been completed, and subsequent tests are currently being planned. This paper addresses the importance of robustness design for localized damage and includes a detailed description regarding how the research program advances the current state of knowledge for assessing robustness of compositely constructed steel-framed buildings.

This paper presents a comparison of two compartment fire experiments performed on the 9.1 m × 6.1 m composite floors using a full-scale two-story steel gravity frame to study the influence of slab reinforcement on the overall structural integrity. The floor specimens were designed to achieve a 2-h fire rating but had dissimilar slab reinforcement. The Test #1 specimen had steel wire reinforcement of 60 mm2/m width as the minimum permitted in the United States practice whereas the Test #2 specimen was reinforced with deformed steel bars (230 mm2/m) determined by incorporating tensile membrane action. The Test #1 specimen exhibited mid-panel slab integrity failure before reaching the specified fire rating period. However, the Test #2 specimen exhibited much smaller concrete cracks until it was heated up to 131 min and retained the post-fire residual strength at least two times greater than the design demand at ambient temperature. This unique large-scale testing demonstrated that the appropriate slab reinforcement scheme can delay the vertical deflection of the heated composite floor and maintain the structural integrity at large vertical displacements over a longer duration of fire exposure. • The influence of slab reinforcement on the structural integrity of steel-concrete composite floors under fire was evaluated. • Compartment fire experiments were conducted on the composite floor assemblies located in a full-scale two-story steel gravity frame. • Slab reinforcement of larger area and ductility can maintain the structural integrity of the slab for longer period of fire. • The enhanced slab reinforcement significantly delayed the increase in the vertical displacement of the composite floor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper concerns the development and experimental validation of prediction models using Statistical Energy Analysis (SEA) to calculate the airborne sound insulation of a timber–concrete composite floor. The complexity in modelling this floor is due to it having (1) a multilayer upper plate formed from concrete and Oriented Strand Board (OSB), (2) multiple types of rigid connector between the upper plate and the timber joists and (3) a resiliently suspended ceiling. A six-subsystem model treats the concrete–OSB plate as a single subsystem and three different five-subsystem models treat the combination of concrete, OSB and timber joists as a single orthotropic plate subsystem. For the orthotropic plate it is suggested that bending stiffnesses predicted using the theories of Huffington and Troitsky provide a more suitable and flexible approach than that of Kimura and Inoue. All SEA models are able to predict the weighted sound reduction index to within 2 dB of the measurement. The average difference (magnitude) between measurements and predictions in one-third octave bands is up to 4 dB. These results confirm that SEA can be used to model direct transmission across relatively complex floor constructions. However, this requires the inclusion of measured data in the SEA model, namely the dynamic stiffness of the resilient isolators and the cavity reverberation time. [ABSTRACT FROM AUTHOR]

This paper presents a plastic hinge analysis approach for static and dynamic assessment of composite frames under column loss scenarios. The proposed plastic hinge analysis method can be implemented using spreadsheet programming and it is computational less expensive compared to numerical analysis. A step-by-step first-order elastic-plastic analysis by tracking the formation of plastic hinge in a composite floor is performed until a collapse mechanism is formed to establish the static load-displacement behaviour and collapse load of a composite floor subject to sudden column loss. Floor deflections corresponding to the formation of each plastic hinge are evaluated to predict the static load-deformation response of composite frame. The composite floor joint effects can be included in the plastic hinge analysis by calculating the joints' axial resistance and moment resistance using the Eurocodes' component method. A dynamic assessment approach is then used to predict the dynamic response of frame due to sudden column loss. The accuracy of the proposed method is verified by comparing the predicted results with those from the established test and numerical results available in the literature. [ABSTRACT FROM AUTHOR]

Large-scale tests and accidental fires have demonstrated that the composite steel-framed buildings have significant load-bearing capacities and are more resilient to fire conditions compared to fire resistance tests performed on the isolated elements. Understanding the beneficial effect of the tensile membrane action will enable minimization of the amount of fire protection measures, which will increase the competitiveness of the use of steel–concrete composite floors in buildings. The fire resilience of floors is dependent on the connection behavior since the failure of the connection might lead to partial collapse of the interior beams. This paper presents a numerical investigation on the performance of a composite steel-framed floor system and the beam-to-beam shear connection at elevated temperatures. The paper also investigates the effect of the interior beams on the concrete slab in terms of vertical deflection, composite action and stress levels in the steel reinforcement. The results show that the single plate shear connection buckles and excessively deforms during the early phases of the fire. The out-of-plane distortion of the plate causes bolts to load in the tension. The connection reaches its rotational and axial capacity during the cooling phase of the fire resulting the bolts to fail with combined shear and tension. [ABSTRACT FROM AUTHOR]

• The characteristics of low-frequency noise and vibration in a high-speed train were investigated. • A lightweight and low-frequency acoustic metamaterial was optimised based on the MIGA. • The influence of installation positions of the acoustic metamaterial on noise control was analysed. • The composite floor with acoustic metamaterials achieved a 3.9 dB low-frequency noise reduction. Low-frequency noise and vibration are new challenges faced in high-speed trains. Conventional sound insulation and absorption materials or structures have insufficient efficiency for low-frequencies. This paper studies how to design lightweight acoustic metamaterials and apply them to high-speed train composite floors, for low-frequency noise and vibration control. First, through in-situ experiments, the interior noise characteristics and sound source distributions of a high-speed train were measured and analysed, including the sound transmission characteristics of the composite floor. Second, based on the finite element method, a vibration analysis model of the composite floor was established and validated. The target frequency of noise and vibration control was determined. Third, based on the multi-parametric optimisation method, a lightweight and low-frequency acoustic metamaterial (beam-like resonator) for the low-frequency noise and vibration control was designed, and the band gap properties of the beam-like resonator were obtained. Finally, the noise reduction effects of the beam-like resonator installed on different positions of the high-speed train composite floor were analysed, including vibration transfer ratio, vibration response and radiated sound power. The results demonstrate that the weight of the optimal beam-like resonator could be reduced by 60.7 %, compared to the initial solution prior to optimisation design. When the beam-like resonators are installed on the wooden floor, the vibration transfer ratio of the target frequency is reduced drastically, the overall acceleration level is reduced by 2.9 dB, and the overall radiated sound power level is reduced by 3.9 dB. The lightweight acoustic metamaterial designed in this paper has an obvious effect on the low-frequency noise and vibration control of composite structures. [ABSTRACT FROM AUTHOR]

According to full-scale fire tests, it is noticed that tensile membrane action within the concrete floor slabs plays an important role in affecting the fire resistance of composite buildings. It is well known that the development of tensile membrane actions relies on the vertical support along the edges of the slab panel. However, there is at present a lack of research into the influence of vertical supports on the tensile membrane actions of the floor slabs. In this paper, the performances of a generic three dimensional 45 m×45 m composite floor subjected to ISO834 Fire and Natural Fire are investigated. Different vertical support conditions and three steel meshes are applied in order to assess the impact of vertical supports on tensile membrane action of floor slabs. Unlike other existing large scale modelling which assumes the connections behave as pinned or rigid for simplicity, two robust 2-node connection element models developed by the authors are used to model the behaviour of end-plate and partial end-plate connections of composite structures under fire conditions. The impact of connections on the 3D behaviour of composite floor is taken into consideration. The load-transfer mechanisms of composite floor when connections fail due to axial tension, vertical shear and bending are investigated. Based on the results obtained, some design recommendations are proposed to enhance the fire resistance of composite buildings. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the most destructive natural phenomena is the earthquake. These events destroy lives, goods and disrupt human activities. For this reason the anti-seismic protection of buildings is a very important and of interest subject in Civil Engineering. In the case of structures with a low seismic energy dissipation capacity (for example steel frame structures with Slimdek composite floors), this problem becomes more complicated due to the requirement of dampers. In this paper an experimental study is presented regarding an innovative yielding metallic energy dissipation device, proposed by the author. An experiment is carried out on a shake table. By studying the results from the experiments and from the previous carried out numerical analysis we can conclude that this device provides a high anti-seismic protection for this type of structures. [ABSTRACT FROM AUTHOR]

The applications of composite materials have been widely practiced in modern construction. Structural engineers are often urged to consider aesthetic values as well as the financial aspects in their work, which results in structures that have long span, lightweight and low natural frequencies. These structures exhibit excessive vibrations that cause major discomforts to the occupants. The purpose of this study is to establish a methodology using finite element analysis for assessing the dynamic responses of composite floors and determining the corresponding level of comfort. Linear elastic finite element analysis was conducted using more realistic load models with respect to the application of different geometries of concrete slab and fiber reinforced polymer materials. The composite floor investigated included FRP deck, FRP beams, and concrete slabs of various thicknesses. The resulting maximum peak accelerations indicated the need for more realistic load models to generate a time function including space, time and heel impact descriptions. The FRP deck or beam was satisfactory in terms of serviceability and comfort level. There were no significant differences between the results when fiber reinforced polymer materials or common concrete-steel composite floors were used. [ABSTRACT FROM AUTHOR]

Using nonlinear finite element analysis method with ANSYS, and changing the spacing among the screws connecting the profiled steel sheet and the steel joists, yield strength of steel, strength of concrete, thickness of C type steel joists, thickness of concrete slab, types of profiled steel sheet, space between steel joists, width of floor, spandepth ratio of steel joists and height to thickness ratio of the web, the flexural capacity and the ductility of composite floor were researched. The research shows, the effects of the spacing among the screws connecting the profiled steel sheet and the steel joists, yield strength of steel, thickness of C type steel joists, types of profiled steel sheet, spacing between steel joists, width of floor, span-depth ratio of steel joists, height to thickness ratio of the web on the flexual capacity of composite floor are remarkable. The strength of concrete has little influence. The flexural capacity of composite floor increases linearly as the thickness of concrete slab changs from 50 mm to 100 mm, and no further improvement can be obtained when the concrete slab is thicker than 100 mm. The strength of concrete, spacing between steel joists and width of floor have little influence on the ductility of composite floor. T-shaped section composite beam model can be used as the simplified calculation model of the composite floor. [ABSTRACT FROM AUTHOR]

Over the past decade, much research has focused on the behaviour of structures following the failure of a key structural component. Particular attention has been given to sudden column loss, though questions remain as to whether this event-independent scenario is relevant to actual extreme events such as explosion. Few studies have been conducted to assess the performance of floor slabs above a failed column, and the computational tools used have not been validated against experimental results. The research program presented in this paper investigates the adequacy of sudden column loss as an idealisation of local damage caused by realistic explosion events, and extends prior work by combining the development of accurate computational models with large-scale testing of a typical floor system in a prototypical steel-framed structure. The floor system consists of corrugated decking topped by a lightly reinforced concrete slab that is connected to the floor beams through shear studs. The design is consistent with typical building practices in the US. The first test has been completed, and subsequent tests are currently being planned. This paper addresses the importance of robustness design for localized damage and includes a detailed description regarding how the research program advances the current state of knowledge for assessing robustness of compositely constructed steel-framed buildings. [ABSTRACT FROM AUTHOR]

Human activity-induced vibrations in slender structural systems become apparent in many different excitation modes and consequent action effects that cause discomfort to occupants, crowd panic and damage to public infrastructure. Resulting loss of public confidence in safety of structures, economic losses, cost of retrofit and repairs can be significant. Advanced computational and visualisation techniques enable engineers and architects to evolve bold and innovative structural forms, very often without precedence. New composite and hybrid materials that are making their presence in structural systems lack historical evidence of satisfactory performance over anticipated design life. These structural systems are susceptible to multi-modal and coupled excitation that are very complex and have inadequate design guidance in the present codes and good practice guides. Many incidents of amplified resonant response have been reported in buildings, footbridges, stadia and other crowded structures with adverse consequences. As a result, attenuation of human-induced vibration of innovative and slender structural systems very often requires special studies during the design process. Dynamic activities possess variable characteristics and thereby induce complex responses in structures that are sensitive to parametric variations. Rigorous analytical techniques are available for investigation of such complex actions and responses to produce acceptable performance in structural systems. This paper presents an overview and a critique of existing code provisions for human-induced vibration followed by studies on the performance of three contrasting structural systems that exhibit complex vibration. The dynamic responses of these systems under human-induced vibrations have been carried out using experimentally validated computer simulation techniques. The outcomes of these studies will have engineering applications for safe and sustainable structures and a basis for developing design guidance. [ABSTRACT FROM AUTHOR]