In this contribution bending and shear tests of cross laminated timber (CLT) plates under concentrated loads are presented. The so loaded structural members can fail either due to punching along a critical perimeter line in the vicinity of the concentrated load or in bending. Two test configurations were developed and investigated by linear elastic models. The obtained test results and observed failures as well as their correlation with the mechanical modeling are shown in this paper. The established numerical model was a 3D solid model with different material behavior for all acting stresses. The material behavior was implemented in a user subroutine for the FE program ABAQUS. By comparison of measured and computed load displacement curves numerical models could be discussed regarding their reliability and conclusions about missing input for an increasing accuracy of the model could be drawn.
This thesis deals with the shear design of Cross Laminated Timber (CLT) elements stressed by concentrated loads which are locally reinforced by means of self-tapping screws with continuous threads. A simplified model is presented using an effective width for the calculation of the shear stresses in the vicinity of point supports or concentrated loads. Laboratory tests supply material-mechanical principles to determine the interaction of rolling shear stresses and compression perpendicular to the grain. In addition to experimental tests theoretical models are developed to examine the load bearing behaviour of CLT-elements reinforced by self-tapping screws. Preliminary tests with plate elements provide initial experience with these reinforcements under biaxial load transfer. Finally a design concept validated by means of the test results is proposed.
Timber-concrete composite (TCC) solutions are not a novelty. They were scientifically referred to at the beginning of the 20th century and they have proven their value in recent decades. Regarding a TCC floor at the design stage, there are some assumptions, at the standard level, concerning the action of concentrated loads which may be far from reality, specifically those associating the entire load to the beam over which it is applied. This naturally oversizes the beam and affects how the load is distributed transversally, affecting the TCC solution economically and mechanically. Efforts have been made to clarify how concentrated loads are distributed, in the transverse direction, on TCC floors. Real-scale floor specimens were produced and tested subjected to concentrated (point and line) loads. Moreover, a Finite Element (FE)-based model was developed and validated and the results were collected. These results show that the “loaded beam” can receive less than 50% of the concentrated point load (when concerning the inner beams of a medium-span floor, 4.00 m). Aiming at reproducing these findings on the design of these floors, a simplified equation to predict the percentage of load received by each beam as a function of the floor span, the transversal position of the beam, and the thickness of the concrete layer was suggested.
In this paper a proposal for the computation of stresses into orthotropic panels (e.g. CLT wall elements) caused by concentrated local load introduction in plane is derived on the basis of linear elastic mechanics. In practice the concept of effective width is often applied for the approximate determination of stresses. On the basis of the elastic solution in this contribution a proposal for the determination of the effective width is submitted. In addition a proposal for the stability verifications by means of the effective width is given..
Installing between-joist bracing can be an economical and effective means of mitigating excessive vibration levels in wood floors associated to human discomfort. Effectiveness of between-joist bracing depends upon its own rigidity that accounts for the location of bracing, geometric arrangement and connection stiffness of installed bracing elements to joist. This paper presents a method to quantify the flexural rigidities of between-joist bracing and their influence on vibrational serviceability parameters such as static deflection under a concentrated load and fundamental natural frequency of timber floor. A designer-usable analytical model, based on ribbed-plate theory, was used to predict static deflection and fundamental natural frequency by taking account of measured bracing rigidities. Results show that predictions the static deflection and natural frequencies. The proposed method and ribbed-plate model could be integrated into current design approaches to predict vibrational performance of timber floors.