Home  About us  Contact
 

Wall Panels (wall + panel)

Distribution by Scientific Domains
Engineering75%

Selected Abstracts

The influence of the construction process on the deformation behaviour of diaphragm walls in soft clayey ground

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2006
R. Schäfer
Abstract Conventional numerical predictions of deep excavations normally neglect the construction process of the retaining structure and choose the earth pressure at rest as initial condition at the beginning of the simulation. The presented results of simulation and measurements during the construction process of the Taipei National Enterprise Center show, that such an assumption leads to an underestimation of the horizontal wall deflection, the surface ground settlements as well as the loading of the struts in case of normally to slightly over-consolidated clayey soil deposits. The stepwise installation process of the individual diaphragm wall panels results in a substantial modification of the lateral effective stresses in the adjacent ground. Especially the pouring process of the panel and the fresh concrete pressure causes a partial mobilization of the passive earth pressure and a distinct stress level increase in the upper half of the wall. As a consequence of the increased stresses prior to the pit excavation, up to 15% greater ground and wall movements are predicted. Moreover, the increased stress level due to the installation process of the diaphragm wall leads to substantial higher strut loadings during the excavation of the pit. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Modelling of earth and water pressure development during diaphragm wall construction in soft clay

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 13 2004
R. Schäfer
Abstract The influence of a diaphragm wall construction on the stress field in a soft clayey soil is investigated by the use of a three-dimensional FE-model of seven adjacent wall panels. The installation procedure comprises the excavation and the subsequent pouring of each panel taking into account the increasing stiffness of the placed fresh concrete. The soft clay deposit is described by a visco-hypoplastic constitutive model considering the rheological properties and the small-strain stiffness of the soil. The construction process considerably affects the effective earth and pore water pressures adjacent to the wall. Due to concreting, a high excess pore water pressure arises, which dissipates during the following construction steps. The earth pressure finally shows an oscillating, distinct three-dimensional distribution along the retaining wall which depends on the installation sequence of the panels and the difference between the fresh concrete pressure and the total horizontal earth pressure at rest. In comparison to FE-calculations adopting the earth pressure at rest as initial condition, greater wall deflections and surface ground settlements during the subsequent pit excavation can be expected, as the average stress level especially in the upper half of the wall is increased by the construction procedure of the retaining structure. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Do realistic reverberation levels reduce auditory distraction?

APPLIED COGNITIVE PSYCHOLOGY, Issue 7 2007
Nick Perham
Acoustically treated ceilings and wall panels can be used as part of a strategy to reduce the impact of background sound on the health and performance of employees by decreasing the reverberation times of the office noise. In this article we examine the impact of two reverberation times upon task performance. A cognitive task known to be a sensitive index of auditory distraction (serial recall) was used to assess the degree of distraction associated with two types of ceiling: a hard ceiling, such as plasterboard, and a soft ceiling, such as an acoustically treated ceiling. Office noise (in the range 65,75,dB (A)) was found generally to be disruptive relative to a quiet control condition but there was no difference in performance with regard to the ceiling types. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Zur Berechnung der klimatisch bedingten Temperaturbeanspruchungen von Außenwandbekleidungen

BAUPHYSIK, Issue 2 2008
Nabil A. Fouad Univ.-Prof.
Außenwandkonstruktionen werden durch die ständig veränderlichen klimatischen Randbedingungen maßgeblich thermischbeansprucht. Durch diese instationären nichtlinearen Temperaturbeanspruchungen können Schäden bis hin zu Standsicherheitsproblemen entstehen. In diesem Beitrag wird anhand eines Beispiels einer Außenwandkonstruktion beschrieben, welche physikalischen Grundlagen und Annahmen für eine instationäre Temperaturfeldberechnung anzusetzen sind und wie eine praxisnahe Berechnung durchgeführt werden kann. Calculation of climatic induced temperature loading of external wall claddings. Exterior wall panels are being mainly thermally loaded due to the changing climatic boundary conditions. This nonlinear transient temperature loading could cause damages for example of the wall cladding and in severe cases even lead to problems conside ring the structural safety of the whole construction. In this paper all the physical basics and assumptions which have to be done for the calculation of the transient temperature fields are introduced and an example of a practical calculation on an exterior wall cladding is shown and discussed. [source]