Lightweight Floor Systems Research Articles

Evaluation on Flexural Performance for Light-Weight Composite Floor with Sound Reduction System

층간소음에 대응할 수 있는 유닛모듈러 경량합성바닥 구조시스템을 제안하고, 이러한 바닥판에 대한 내력 및 거동을 실험연구를 통해 평가하고자 하는 것이 본 연구의 목표이다. 평데크와 철근트러스 데크를 활용하여 제안된 형상별로 각각 3개씩 총 9개의 경량합성바닥판 실험체를 제작하여 실험을 수행하였다. 실험결과, 실험체의 파괴 형태는 바닥판의 중앙부에서 처짐으로 인한 휨변형에 의해 지배되었으며 종국으로 바닥판 상부에 콘크리트 압괴가 발생하는 동일한 파괴양상을 나타내었다. 또한, 사용하중 상태에서는 구조적으로 안전하고, 사용성 측면에서도 우수한 것으로 나타났다. 이론적 공칭하중에 대한 실험 항복하중의 비는 0.86~1.27의 분포로 평균 1.04로 나타났으며, 분포도 측면에서 변동계수는 0.154로 나타나 비교적 잘 일치하는 것으로 나타났다. The purpose of this study is to propose structural technologies on the light-weight composite floor systems in the unit modular and to evaluate structural performance of the composite floor through flexural experiments. The flexural experiments were carried out on total nine specimens(each three type in shape) using steel flat deck and truss deck. From the results of test, all specimens showed the same failure patterns which exhibited deflection at the center of the specimens due to flexural deformation before concrete crushing at the upper of specimens. Also, we know that the proposed floors satisfied in serviceability and would be safe sufficiently. The ratio of experimental yield load by theoretical nominal load was the distribution of 0.86 to 1.27 with an average 1.04. Coefficient of variation in distribution showed good agreement.

Mitigating footfall-induced vibration in long-span floors

Long-span lightweight floor systems with low damping are susceptible to serviceability problems due to human excitations. This paper discusses two remedial measures to alleviate disturbing footfall-induced vibrations observed on a real office floor of steel-concrete composite construction. One treatment involves stiffening the existing floor beams while the other utilises passive control with an innovative distributed multiple viscoelastic tuned mass damper (TMD) system. Several finite element models reflecting different remedial scenarios are analysed from which the TMD approach and the traditional stiffening technique are found to be comparably effective in reducing the vibration level. However, the proposed TMD solution is far superior, feasible and non-intrusive when applied to existing floors. A probability-based evaluation of the effectiveness of the TMD system is also conducted, taking into account likely variations in the walking force and dynamic properties of both the floor and dampers. The custom-made damper system has been successfully installed on the real floor and performed efficiently in various field tests.

Mitigating Footfall-Induced Vibration in Long-Span Floors

Long-span lightweight floor systems with low damping are susceptible to serviceability problems due to human excitations. This paper discusses two remedial measures to alleviate disturbing footfall-induced vibrations observed on a real office floor of steel-concrete composite construction. One treatment involves stiffening the existing floor beams while the other utilises passive control with an innovative distributed multiple viscoelastic tuned mass damper (TMD) system. Several finite element models reflecting different remedial scenarios are analysed from which the TMD approach and the traditional stiffening technique are found to be comparably effective in reducing the vibration level. However, the proposed TMD solution is far superior, feasible and non-intrusive when applied to existing floors. A probability-based evaluation of the effectiveness of the TMD system is also conducted, taking into account likely variations in the walking force and dynamic properties of both the floor and dampers. The custom-made damper system has been successfully installed on the real floor and performed efficiently in various field tests.

Dynamic performance characteristics of an innovative Hybrid Composite Floor Plate System under human-induced loads

This study explored the dynamic performance of an innovative Hybrid Composite Floor Plate System (HCFPS), composed of Polyurethane (PU) core, outer layers of Glass–fibre Reinforced Cement (GRC) and steel laminates at tensile regions, using experimental testing and Finite Element (FE) modelling. Experimental testing included heel impact and walking tests for 3200mm span HCFPS panels. FE models of the HCFPS were developed using the FE program ABAQUS and validated with experimental results. HCFPS is a light-weight high frequency floor system with excellent damping ratio of 5% (bare floor) due to the central PU core. Parametric studies were conducted using the validated FE models to investigate the dynamic response of the HCFPS and to identify characteristics that influence acceleration response under human induced vibration in service. This vibration performance was compared with recommended acceptable perceptibility limits. The findings of this study show that HCFPS can be used in residential and office buildings as a light-weight floor system, which does not exceed the perceptible thresholds due to human induced vibrations.

Improving a current method for predicting walking-induced floor vibration

Serviceability rather than strength is the most critical design requirement for vibration-vulnerable floor constructions. Annoying vibrations due to normal walking activity have been observed more frequently on long-span lightweight floor systems in office and commercial retail buildings, raising the need for the development of floor vibration design procedures. This paper highlights some limitations of one of the most commonly used guidelines AISC/CISC DG11, and proposes improvements to this method. Design charts and approximate closed form formulas to estimate the walking response are developed in which various factors relating to the dynamic characteristics of both the floor and the excitation are considered. The accuracy of the proposed formulas and other proposals found in the literature is examined. The proposed modifications would be significant, especially with long-span floors where vibration levels may be underestimated by the current design procedure. The application of the proposed prediction method is illustrated by worked examples that reveal a good agreement with results obtained from finite element analyses and experiments. The presented work would enhance the accuracy and maintain the simplicity and convenience of the design guideline.

Performance of Distributed Multiple Viscoelastic Tuned Mass Dampers for Floor Vibration Applications

Floor vibration due to human activities is becoming a significant concern to designers and developers of long span lightweight floor systems. Modern office floors are now constructed with longer spans and lighter structural members. Actual office dead loads and floor damping are significantly lower than what they were in the past, increasing the potential for annoying floor vibration. Traditional techniques to reduce vibrations through structural modifications have some serious shortcomings, especially with existing structures. This paper discusses the development of an innovative configuration for a tuned mass damper (TMD) using viscoelastic material in rectifying problematic floors. General analytical formulae to predict the response of a floor fitted with multiple identical TMDs are developed. Experimental and numerical studies on the performance of a custom-made distributed multiple viscoelastic TMD system in suppressing the vibration level on an actual office floor subjected to various types of excitations are discussed. The effects of the damper location, the variation in the floor and/or dampers dynamic characteristics on the effectiveness of this control approach have been taken into account. The installed damper system has successfully suppressed the floor response level to an acceptable limit for human comfort, in the case study presented.

Design of lightweight floor system for optimized vibration comfort

A major trend in current building practice is to reduce the weight of structures. The main incentives for this trend are the scarcity of materials and the rising costs of labor and materials. This is one of the goals of IFD (Industrial, Flexible and Demountable) way of building which is the prevalent Dutch approach to sustainable building. One of the heaviest and most complex parts of a building is the floor. Therefore the focus of this research is to develop a lightweight floor system. However, these lightweight floor systems are sensitive to vibrations and are therefore, without taking measures, regarded less comfortable than heavier, more traditional floor systems. This paper describes structural measures to increase vibration comfort. A quality measure, based on the velocity of the vibration, is used to compare the comfort value of a structure subjected to vibrations. This quality measure includes human sensitivity for vibration that is frequency dependent. The structural measures include intelligent ...

Design of Lightweight Floor System for Optimized Vibration Comfort

A major trend in current building practice is to reduce the weight of structures. The main incentives for this trend are the scarcity of materials and the rising costs of labor and materials. This is one of the goals of IFD (Industrial, Flexible and Demountable) way of building which is the prevalent Dutch approach to sustainable building. One of the heaviest and most complex parts of a building is the floor. Therefore the focus of this research is to develop a lightweight floor system. However, these lightweight floor systems are sensitive to vibrations and are therefore, without taking measures, regarded less comfortable than heavier, more traditional floor systems. This paper describes structural measures to increase vibration comfort. A quality measure, based on the velocity of the vibration, is used to compare the comfort value of a structure subjected to vibrations. This quality measure includes human sensitivity for vibration that is frequency dependent. The structural measures include intelligent coupling of structural elements and support conditions. A detailed study on the effects of these structural measures and a design principle with improved vibration comfort will be presented.

Connection stiffness and natural frequency of DuraGal lightweight floor systems

This paper reports a series of component tests on a lightweight floor system and a method to predict the natural frequency of the floor using a frame analysis program. Full-scale floor tests are also briefly described. DuraGal steel Rectangular Hollow Sections (in-line galvanised RHS) are used as joists, bearers and piers in DuraGal lightweight floor systems. A structural grade particleboard is used as decking. Connection stiffness between different components (bearer, joist, pier and floor decking) was determined. A 40% composite action was achieved between the RHS joist and the particleboard. Both 2D and 3D models were developed to study the effect of connection stiffness on predicting the natural frequency of DuraGal lightweight floor systems. It has been found that the degree of shear connection between the bearer and the joist has a significant influence on the floor natural frequency. The predicted natural frequencies are compared with measured values from full scale floor testing.

Optimal Placement of Actuators and Sensors for Floor Vibration Control

Lightweight floor systems are susceptible to excessive levels of vibration caused by occupant activities such as walking, dancing, and aerobics. Ongoing research utilizes active control to reduce vibration. Placement of multiple actuators and sensors for effective vibration control of flexible systems such as floors is a challenging task. The method proposed in this paper simultaneously determines optimal placements for multiple actuators, sensors, and appropriate output feedback gains of the controller. Instead of carrying out the controller design in the analog domain and then applying a transformation to arrive at a digital implementation, the proposed algorithm provides a digital controller directly. This allows lower sampling rates to be used at the implementation stage. To obtain faster settling times in the presence of external disturbances, a performance index that penalizes system states exponentially is utilized. The nonlinearities associated with actuator saturation due to force/stroke limitations is considered explicitly in the optimization. The proposed algorithm uses an interpolation scheme in case only partial knowledge of the mode shape is available. Hence it is applicable to a wider class of 2D structures that do not possess closed-form expressions for modal shapes and for which one has to resort to finite-element or experimental modal analysis.

Active Control Approach for Reducing Floor Vibrations

Large floor vibration amplitudes can produce disruption and reduced efficiency in employees, and in more extreme cases can result in complete abandonment of a structure for its intended use. The implementation of active control to reduce vibration levels in lightweight floor systems is explored in this paper. A velocity feedback scheme has been developed in which an electromagnetic proof-mass actuator is used to impart control forces on a floor system, thus, reducing the amplitudes of the floor motion. The development, analysis, and experimental verification are discussed for the successful implementation of this control application. A full-scale experimental test floor was designed, constructed, and modeled analytically for this study. Both analytical and experimental results for the floor response to transient excitation show an increase in damping from approximately 2.5% to 40%. Experimental results for walking excitation show a reduction of peak velocity amplitudes to 12% of amplitudes recorded for the uncontrolled system.