scholarly journals The Influence of Improved Strength Grading In Situ on Modelling Timber Strength Properties

Buildings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 30
Author(s):  
Maria Loebjinski ◽  
Wolfgang Rug ◽  
Hartmut Pasternak
Keyword(s):  
Bearing Capacity ◽  
Strength Properties ◽  
Material Strength ◽  
Timber Species ◽  
Load Bearing Capacity ◽  
Visual Evaluation ◽  
Load Bearing ◽  
Existing Structures ◽  
Ultrasonic Time

The management and preservation of structures in our built environment are central and challenging tasks for practicing engineers. Within the CEN member states (European Committee for Standardization), the so-called Eurocodes form the basis of the design and verification of the load-bearing capacity of structures. Current Eurocodes do not contain special recommendations for existing structures, meaning that the principles for new structures are applied. This can lead to an incorrect estimation of the load-bearing capacity within the semi-probabilistic safety concept. A central task within the investigation and evaluation of existing structures is the strength grading of the material in situ using non-/semi-destructive technical devices. Studies show the potential of the ultrasonic time-of-flight measurement in combination with visual evaluation for an improved grading. The information on the material from an improved grading technique can be used to update the material parameters as a target variable using a measured reference variable. In this contribution, test data from a partner project (spruce, pine, and oak) are analyzed, applying the stochastic grading model of Pöhlmann and Rackwitz. It can be shown that different grading techniques influence the updated distribution function of the material strength within the grade. The results depend on the timber species. Perspectives to develop updated models dependent on the knowledge available are shown and discussed.

Assessment of Load-Bearing Capacity of Bridges

2017 ◽  
Vol 259 ◽  
pp. 113-118 ◽  
Author(s):  
Jaroslav Navrátil ◽  
Michal Drahorád ◽  
Petr Ševčík
Keyword(s):  
Bearing Capacity ◽  
Prestressed Concrete ◽  
Iterative Solution ◽  
Concrete Bridges ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Prestressed Concrete Bridges ◽  
Existing Structures ◽  
Non Linear

The paper aims to the determination of load-bearing capacity of reinforced/prestressed concrete bridges subjected to the combination of all components of internal forces according to Eurocode standards for assessment of existing structures. Undoubtedly bridge load rating is laborious hand-iterative process, especially when it comes to reinforced and/or prestressed concrete bridges. The engineer can spend days and weeks trials and errors in the estimation of bridge load-carrying capacity. The problem lies in the determination of load-bearing capacity of cross-section subjected to the combination of normal and shear forces, bending and torsional moments. Due to the different effects of permanent and variable loads and the non-linear behavior of structural materials, the problem becomes non-linear and its solution requires the use of suitable iterative method. Optimized iterative solution was implemented into IDEA StatiCa software and the results are presented in this paper.

scholarly journals In situ Determination of Load Bearing Capacity of Soils on the Airfields

2015 ◽  
Vol 15 ◽  
pp. 11-18 ◽  
Author(s):  
Martin Decký ◽  
Eva Remišová ◽  
Martin Mečár ◽  
Ladislav Bartuška ◽  
Ján Lizbetin ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Load Bearing Capacity ◽  
Load Bearing

The Study of Post-Fire Load Bearing Capacity of Steel Column under Axial Compression Exposure to one-Side Fire

2011 ◽  
Vol 284-286 ◽  
pp. 330-334
Author(s):  
Jian Feng Chen ◽  
Tian Hua Zhou ◽  
Lin Feng Lu ◽  
Han Heng Wu
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Load Condition ◽  
Heterogeneous Material ◽  
Material Strength ◽  
Fire Load ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Steel Column ◽  
Uniform Temperature Field

The section of steel column under axial compression presents heterogeneous material and its load condition changes after experiencing fire damage of one side. Taking H-section steel column under axial compression commonly used in engineering for study object in this thesis in order to study post-fire residual load bearing capacity, the post-fire eccentric effect of steel column under axial compression exposure to one-side fire is analyzed using the method of equivalent section which considering the change of the material strength after high temperature, the influence of non-uniform temperature field on material properties and the stiffness degradation of member section. Calculation methods of the eccentricity and additional moment are proposed and further given a formula of residual load bearing capacity.

scholarly journals MECHANICAL BEHAVIOUR OF TIMBER‐TO‐CONCRETE CONNECTIONS WITH INCLINED SCREWS

2007 ◽  
Vol 13 (3) ◽  
pp. 201-207 ◽  
Author(s):  
Saulius Kavaliauskas ◽  
Audronis Kazimieras Kvedaras ◽  
Balys Valiūnas
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Ultimate Load ◽  
Strength Properties ◽  
High Tensile Strength ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Plastic Failure ◽  
Axial Tension ◽  
Concrete Joints

The purpose of this paper is to adopt the Johansen's yielding theory as a possibility to predict the ultimate load for timber‐to‐concrete joints using self‐tapping threaded connectors screwed at an angle into the wood. The ultimate load‐bearing capacity of a single connector is predicted to be when either the stresses in the wood reach the plastic failure stress level or when a combination of plastic failure in wood and dowel is attained. K. W. Johansen assumed that no axial tension occurred in the dowel and, thus no frictional contribution affected the lateral load‐bearing capacity. However, the joints with inclined fasteners are first affected by tension load, so the withdrawal capacity of the screws has to be taken into account. In order to determine the load bearing capacity for specific connector geometry, the kinematical possible failure modes are determined. The screw in the concrete part of connection was taken as rigidly embedded and thus no deformations appeared. The study showed that the load‐bearing capacity for connections with inclined high tensile strength screws can be predicted using the yielding theory, but this theory was unable to predict precisely the failure mode. Possible reasons for that include limited fastener ductility and influence of the screw inclination on the strength properties of timber.

scholarly journals DEVELOPMENT OF A METHOD FOR CALCULATING THE BEARING CAPACITY OF BORED CONICAL PILES

2021 ◽  
Vol 6 (9) ◽  
pp. 28-36
Author(s):  
I. Rybnikova ◽  
A. Rybnikov
Keyword(s):  
Bearing Capacity ◽  
Field Tests ◽  
Side Surface ◽  
Strength Properties ◽  
Empirical Method ◽  
Full Scale ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Static Tests ◽  
Ground Resistance

Three methods for determining the load-bearing capacity of bored conical piles are presented, considering the additional forces of the ground rebound along their inclined side surface under vertical load. It is proposed to determine the bearing capacity according to the results of field tests using the coefficient of transition from the maximum permissible settlement of the building foundation to the settlement of the pile obtained during static tests. Its value varies from 0.1 to 0.3 depending on the angle of the pile taper. To determine the bearing capacity of the empirical method, tabular data of the ground rebound forces on the side surface of the piles are developed. It depends on the strength properties of the base soil, the angle of the pile taper and the depth of the location of the changing cross-section of the pile along the length. The process of compressing the soil in a drilled well with an elastic cylindrical pressiometer is close to the occurrence of a ground rebound when it is pushed apart by the side surface of a conical pile during sediment under load. It is proposed to determine the ground resistance on the side surface of conical piles according to the same dependence as when processing the results of pressiometric tests of soils, taking into account the introduction of a correction factor depending on the parameters of the pile. The calculated load-bearing capacity of the piles, determined by the proposed methods, differs from the actual load-bearing capacity, determined by the results of static tests of full-scale piles, within 10 %. However, these methods need to be improved with the accumulation of statistical data for testing full-scale piles in different ground conditions.

scholarly journals The Influence of CFRP Sheets on the Load-Bearing Capacity of the Glued Laminated Timber Beams under Bending Test

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4019
Author(s):  
Klaudia Śliwa-Wieczorek ◽  
Krzysztof Adam Ostrowski ◽  
Justyna Jaskowska-Lemańska ◽  
Anna Karolak
Keyword(s):  
Bearing Capacity ◽  
Standard Procedure ◽  
Bending Test ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Existing Structures ◽  
Reinforced Beams ◽  
Glued Laminated Timber ◽  
Before And After ◽  
Timber Beams

Composite materials are increasingly used to strengthen existing structures or new load-bearing elements, also made of timber. In this paper, the effect of the number of layers of Carbon Fiber Reinforced Polymer (CFRP) on the load-bearing capacity and stiffness of Glued Laminated Timber beams was determined. Experimental research was performed on 32 elements—a series of eight unreinforced beams, and three series of eight reinforced beams: with one, three and five layers of laminate each. The beams with a cross-section of 38 mm × 80 mm and a length of 750 mm were subjected to the four-point bending test according to standard procedure. For each series, destructive force, deflection, mode of failure, and equivalent stiffness were determined. In addition, for the selected samples, X-ray computed tomography was performed before and after their destruction to define the quality of the interface between wood and composite. The results of the conducted tests and analyses showed that there was no clear relationship between the number of reinforcement layers and the load-bearing capacity of the beams and their stiffness. Unreinforced beams failed due to tension, while reinforced CFRP beams failed due to shear. Despite this, a higher energy of failure of composite-reinforced elements was demonstrated in relation to the reference beams.

Investigation of the load-bearing behavior of composite joints in cross-section supplements for concrete structures

2021 ◽  
Author(s):  
Christian Knorrek ◽  
Sven Bosbach ◽  
Josef Hegger
Keyword(s):  
Bearing Capacity ◽  
Structural Concrete ◽  
Load Bearing Capacity ◽  
Research Project ◽  
Cross Sectional ◽  
Ongoing Research ◽  
Load Bearing ◽  
Existing Structures ◽  
Composite Joint ◽  
Bearing Behavior

<p>The strengthening with cross-sectional supplements made of reinforced concrete is already of great importance in building, bridge, and industrial constructions and will be further developed in the future because of the increasing demands on existing structures [1]- [3].</p><p>As part of an ongoing research project at the Institute of Structural Concrete at RWTH Aachen University, funded by the German Federation of Industrial Research Associations (AiF), a correlation between the method of surface treatment of the old concrete, the measured roughness, the type of concrete supplementation, and the load-bearing capacity of the composite joint has to be derived by means of new systematic test series. As a result, a database, and a possible practical guide on the load-bearing capacity of different combinations of old concretes, surface treatments, supplementary concrete layers, and bonding conditions will be developed. This paper will present the initial findings from this research project.</p>

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