This paper examines a new and very promising concept for prefabricated timber-concrete-composite floors (TCC-floors), were the heavy normal weight concrete is replaced by a lightweight concrete (LC) with a density of about 17 kN/m³. Investigations into the connections between lightweight concrete and timber indicate that the performances of the existing connection types are unsatisfactory if combined with lightweight concrete. Therefore, a new connection method is proposed, adhesively bonding the lightweight concrete with the timber by means of a filled epoxy resin. Different ways of manufacturing the bonded timber-lightweight concrete-composite beams (TLCC-beams) are investigated in a research project at the Technische Universität Berlin, to examine the differences in their structural performances. Most promising are the test results for TLLC-beams, fabricated with a wet-in-wet bonding method.
In the presented paper, results of theoretical and experimental investigation of timber-concrete composite members with adhesive connection are described. For the timber part of composite beams Cross Laminated Timber and for concrete part lightweight concrete was used. For the composite connection special adhesive to bounding wet concrete and timber was applied. For experimental investigation two types of composite beams with different dimensions was used. Due to the shrinkage of lightweight concrete small precamber of timber beams during concrete hardening was applied. CLT panels combined with concrete slab dispose of higher load-carrying capacity, lower deformation and vibration. In case of theoretical analysis, simplified analytical -method was used to consider shear flexibility of the CLT cross layer. Results of presented experimental and theoretical analysis provide wider scope for further research and application of adhesively bonded CLT-concrete composite members.
Traditionally, multi-family houses have been constructed using heavy, homogenous materials like concrete and masonry. But as a consequence of the progress of lightweight building systems during the last decades, it has been questioned whether standardized sound insulation evaluation methods still are appropriate.
An extensive measurement template has been applied in a field survey where several vibrational and acoustical parameters were determined in ten Swedish buildings of various constructions. In the same buildings, the occupants were asked to rate the perceived annoyance from a variety of natural sound sources. The highest annoyance score concerned impact sounds, mainly in the buildings with lightweight floors.
Statistical analyses between the measured parameters and the subjective ratings revealed a useful correlation between the rated airborne sound insulation and R0 w þ C50—3150 while the correlation between the rated impact sound insulation and L0 n;w þ CI;50—2500 was weak. The latter correlation was considerably improved when the spectrum adaptation term with an extended frequency range starting from 20 Hz was applied. This suggests that frequencies below 50 Hz should be considered when evaluating impact sound in lightweight buildings.
This paper describes the design of a system to monitor floor vibrations in an office building and an analysis of several months worth of collected data. Floors of modern office buildings are prone to occupant-induced vibrations. The contributing factors include long spans, slender and flexible designs, use of lightweight materials and low damping. As a result, resonant frequencies often fall in the range easily excited by normal footfall loading, creating potential serviceability problems due to undesirable levels of vibrations. This study investigates in-situ performance of a non-composite timber-concrete floor located in a recently constructed innovative multi-storey office building. The floor monitoring system consists of several displacement transducers to measure long-term deformations due to timber and concrete creep and three accelerometers to measure responses to walking forces, the latter being the focus of this paper. Floor response is typically complex and multimodal and the optimal accelerometer locations were decided with the help of the effective independence-driving point residue (EfI-DPR) technique. A novel approach to the EfI-DPR method proposed here uses a combinatorial search algorithm that increases the chances of obtaining the globally optimal solution. Several months worth of data collected by the monitoring system were analyzed using available industry guidelines, including ISO2631-1:1997(E), ISO10137:2007(E) and SCI Publication P354. This enabled the evaluation of the floor performance under real operating conditions.
This paper aims to discuss timber-wood lightweight concrete composites for application in wall components for buildings. The aim is to develop a multi-layer wall system composed of wood lightweight concrete, connected timber sections to gain and use advantages of each used material – lightweight, structural, thermal storage and insulation, ecological and economic benefits – to name the most important ones. The development of timber-wood lightweight concrete composites systems will lead to a new generation of polyvalent multi-material building components. By using renewable resources, waste products of the forest industry, and manufactured wood products, this technology provides statically and energy-efficient components for low-energy constructions. Such products support rapid-assembly construction methods, which use prefabricated dry elements to increase the efficiency of the construction. Wood-based alternatives to conventional concrete or masonry construction also open opportunities to reduce the carbon emissions.
Within several research projects and with the aim to optimize energy efficiency and ecological characteristics of structural building components the Department of Structural Design and Timber Engineering (ITI) at the Vienna University of Technology (VUT) developed several wood-based composite systems, which combine timber products with other conventional building materials and components. As a representative example for these developments, the application of wood lightweight concrete composites illustrates the extent of interrelationships in the development of complex system solutions when focusing on the increase of resource efficiency. The environmental assessment shows the ecological advantages of the developed concept compared to conventional concrete elements and underlines the potential for further developments. Assessment of structural wood-based wood lightweight concrete composites are illustrated in this paper.