Hardwood - Softwood Combination in Glued Laminated Timber Cross-Section

Glued laminated timber (glulam), as one of the types of engineered wood products, is in our conditions most often made of coniferous, specifically spruce wood. In order to find optimal usage of material, some new configurations of cross-sections are being suggested. An advanced solution of glulam cross-section could be represented by cross-section formed from combination of hardwood (from deciduous trees) and softwood (from conifers). This paper deals with a possibility of combination of outer lamellas from a hardwood and inner lamellas from a softwood in glulam cross-section. The solution is focused on members suitable for a use in a skeleton frame. Attention is paid to two types of structural members: beam and column. Results of theoretical study are presented which arise from an analytical calculation and from a numerical modelling. For comparison, the calculations were carried out for a reference cross-section consisting of softwood lamellas only. By comparing the combined and reference crosssections, it can be stated that the use of the combined cross-section can save material for both the compression member (column) and the member subjected to bending moment (beam, girder). The combined cross-section appears to be more advantageous than the reference crosssection, especially in cases of smaller beam depth

Numerical Analysis of Influence of Axial Force on Resistance of Column Webs in Transverse Compression

Steel members of double-symmetrical open cross-sections are often used in engineering structures and structures of buildings as columns and beams. Due to connections of the members, transverse compression of the cross-section webs can occur and is subject to structural assessment. The resistance of the column web is influenced by structural solution of the joint (welded, bolted, with end plates) and possible interaction with axial force in the column or shear. The paper focuses on numerical investigation and quantification of the influence of axial force in the column on behaviour and resistance of the column web in transverse compression. The analysis was performed using finite element method based computation system and included both rolled and welded cross-sections with various values of relative slenderness of the web. The results were compared with results of transverse compression resistance calculated using actual standard for design of steel structures

Candidates for volcanoes under the ice of Antarctica detected by their gravito-topographic signal

We analysed the newest gravity field models (given in the form of spherical harmonic expansion to degree and order 2190) EIGEN 6C4 and RET 14, which consist basically from the gravity data from EIGEN 6C4 plus the bedrock topography from the Bedmap 2 model, describing the topography of the ground under the ice of Antarctica. From these models we computed the gravity anomalies, the Marussi tensor of the second derivatives of the disturbing potential, the gravity invariants and their specific ratio, the strike angle and the virtual deformations. We applied these results for a selected part of Antarctica; not too far from the Lake Vostok we discovered at least two objects that might be subglacial volcanoes. We present all predictors and arguments we have available to support this hypothesis, but we are well aware that the "last word" waits for other specialists. We provide geographic coordinates on the ice surface where to dig for the possible volcanoes.Web of Science606art. no. S066

On feasibility to detect volcanoes hidden under the ice of Antarctica via their “gravitational signal”

Many undiscovered volcanoes may be hidden under the thick layers of the ice of Antarctica. Hypothetic volcanoes were sought by means of the best present-day gravitational data (gravity field model EIGEN 6C4) and bedrock topography data (Bedmap2). A new previously unused method was tested. The analogy with the “gravitational signal” typical for volcanoes and other structures in other parts of the Earth is used. Various functions (not only ordinary gravity anomalies) of the disturbing geopotential were employed: Marussi tensor of the second derivatives, geopotential invariants, the strike angle and the virtual deformations. We attempted to discover if the best present-day gravitational and topographic data are of sufficient precision and resolution and how fast is the attenuation of the “gravitational signal” of a volcano with increasing depth under the ice. It is shown that there is no principal obstacle to detect volcanoes by our method. However, it appeared very quickly that our present-day attempts to discover such volcanoes could hardly be successful, mainly due to a low resolution of the existing gravity data and also due to a low resolution of the best bedrock topography of Antarctica currently available. Nevertheless, some examples of hypothetical volcanoes under the ice are given, but they are uncertain. However, the method, the main goal of this feasibility study, is ready and working.

Sandwich Composite Panels With Gfrp Face Sheets – Experimental Analysis, Numerical Simulation and Analytical Solution

This paper deals with the problem of analysis of beams made of SCP (sandwich composite panel) composed of GFRP face sheets and foam core. In the frame of research project, several specimens of different compositions were tested by four-point bending according to the actual standard. Nonlinear behaviour was observed in some specimens and possible reasons are discussed in the paper. SCP beams were also numerically simulated using the finite element method in ANSYS Workbench software. For practical and easy engineering design (prediction of deformations and stresses) the analytical procedure was developed for linear and nonlinear behaviour. Results represented by P-Δ and P-σ diagrams of experimental, numerical, and theoretical analysis are compared together in this paper. Based on the analytical solution the parametric study was performed to find out the optimal composition of SCP members for specific static boundary conditions

Gravito-topographic signal of the Lake Vostok area, Antarctica, with the most recent data

By using SatGravRET2014 gravito-topography model, based also on satellite GRACE and GOCE data, we cornputed and plotted the gravity disturbances, the Marussi tensor of the second derivatives of the disturbing potential, the gravity invariants and their specific ratio, the strike angle and the virtual deformations for the Lake Vostok (LV) area in Antarctica. This set of gravity "aspects" provides more detailed and clearer information than the traditional gravity anomalies. Maps with the bedrock topography from Bedmap 2 are added. Some of our estimates and results confirm independent findings of other specialists, some results presented here are new. LV is divided not only into its N and S parts by a ridge, but also to E and W parts. A tension across LV has a prevailing direction E-W. We identified at least three candidates for subglacial lakes south of the lakes 90 E and Sovetskaya. In the gravity aspects this area looks like a basin, where the mentioned lakes might be just a remnant of a large bowl; the orientation of this basin is the same as that of LV; the size comparable to LV. A subglacial connection between all the mentioned lakes is possible and documented via the gravity aspects, namely by the virtual deformations.Web of Science17745