scholarly journals Fatigue and crack propagation investigations on composite dowels using an inclined single push-out test

2018 ◽  
Author(s):  
Kevin Wolters ◽  
Markus Feldmann
Keyword(s):  
Crack Propagation ◽  
Bearing Capacity ◽  
Fatigue Behaviour ◽  
Steel Part ◽  
Stress Distributions ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Composite Joint ◽  
Residual Capacity ◽  
Push Out

The current fatigue design of composite dowels is based on the structure stress concept for the steel part and upper load limitations to avoid concrete fatigue and a degradation of the composite joint. Therefore the aim of the existing concept is to avoid any fatigue of the composite structure. A fatigue concept considering residual load bearing capacity of torn steel connectors and the transfer of forces to less stressed composite dowels in the beam has great economic potential and leads to a better safety assessment. Therefore, further investigations of fatigue behaviour and crack propagation of composite dowels are necessary. In a first step a single composite dowel is investigated in small-part tests. By the use of finite element models a new inclined single push-out test stand has been developed in order to reproduce the force and stress distributions within a composite beam as precisely as possible with the small-part tests. This ensures the comparability of the crack initiation location and crack propagation. In the test series the influences of different stress ranges and cycle numbers on crack propagation of the steel dowel are investigated. Furthermore the residual load-bearing capacity is determined and compared to static load-bearing behaviour of uncracked steel parts of composite dowels. This paper concentrates on the numerical evaluation of crack propagation and residual capacity.

Holz-Beton-Verbundbauweise: Gebrauchstauglichkeit und Tragfähigkeit von Vollgewindeschrauben zur Sanierung bestehender Holzbalkendecken/Timber-Concrete-Composite Construction: Serviceability and load bearing capacity of full threaded screws for refurbishment of existing timber ceilings

Bauingenieur ◽  
2016 ◽  
Vol 91 (03) ◽  
pp. 103-109
Author(s):  
Maximilian Brunner ◽  
Daniel Rubin ◽  
Gerhard Lener ◽  
Roland Maderebner
Keyword(s):  
Bearing Capacity ◽  
Composite Construction ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Push Out

Erste Untersuchungen und Anwendungen der Holz-Beton-Verbundbauweise liegen nun beinahe 100 Jahre zurück. Vor allem nach dem 2. Weltkrieg wurde diese Bauweise wegen der begrenzten Verfügbarkeit von Eisen verstärkt genutzt. Erst mit der Zeit wurden durch die erhöhten Anforderungen an den Hochbau, vor allem hinsichtlich des Schallschutzes, die weiteren Vorteile dieser Bauweise ersichtlich. Die Hauptanwendung liegt heute auch in der Sanierung und Ertüchtigung bestehender Tragwerke. Der Tragwerksplaner ist dabei immer wieder mit alten Holzbauteilen konfrontiert, die teilweise nur mehr bedingt nach heutigen Sortierkriterien Festigkeitsklassen zuordenbar sind. Speziell für diese Bauaufgabe werden zur Herstellung der Verbundwirkung und Übertragung der Schubkräfte meist stiftförmige Verbindungsmittel verwendet.   Ziel der hier vorgestellten Untersuchungen ist es unter Rahmenbedingungen die denen der Baupraxis möglichst nahe kommen, zu überprüfen, in wie weit handelsübliche Vollgewindeschrauben für diesen Einsatz geeignet sind. Dafür werden durch Push-Out-Versuche die Schubtragfähigkeiten und Verschiebungsmodulen bestimmt. Um Vergleiche mit einem für die Holz-Beton-Verbundbauweise bauaufsichtlich zugelassenem System führen zu können, werden parallel dazu unter denselben Bedingungen Versuche durchgeführt. Dafür konnten im Rahmen der Sanierung eines Altstadthauses Holzbalken für die Prüfkörper der Push-Out-Tests zur Verfügung gestellt werden.

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>

Increased load bearing capacity of mechanically joined FRP/metal joints using a pin structured auxiliary joining element

2020 ◽  
Vol 62 (1) ◽  
pp. 55-60
Author(s):  
Per Heyser ◽  
Vadim Sartisson ◽  
Gerson Meschut ◽  
Marcel Droß ◽  
Klaus Dröder
Keyword(s):  
Bearing Capacity ◽  
Load Bearing Capacity ◽  
Load Bearing

Load-Bearing Capacity of Direct Inlay-Retained Fibre-reinforced Composite Fixed Partial Dentures with Different Cross-Sectional Pontic Design

2017 ◽  
Vol 68 (1) ◽  
pp. 94-100
Author(s):  
Oana Tanculescu ◽  
Adrian Doloca ◽  
Raluca Maria Vieriu ◽  
Florentina Mocanu ◽  
Gabriela Ifteni ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Fracture Pattern ◽  
Load Bearing Capacity ◽  
Cross Sectional ◽  
Load Bearing ◽  
Reinforced Composite ◽  
Polyethylene Fibre

The load-bearing capacity and fracture pattern of direct inlay-retained FRC FDPs with two different cross-sectional designs of the ponticwere tested. The aim of the study was to evaluate a new fibre disposition. Two types of composites, Filtek Bulk Fill Posterior Restorative and Filtek Z250 (3M/ESPE, St. Paul, MN, USA), and one braided polyethylene fibre, Construct (Kerr, USA) were used. The results of the study suggested that the new tested disposition of the fibres prevented in some extend the delamination of the composite on buccal and facial sides of the pontic and increased the load-bearing capacity of the bridges.

scholarly journals The energy absorption behavior of novel composite sandwich structures reinforced with trapezoidal latticed webs

2021 ◽  
Vol 60 (1) ◽  
pp. 503-518
Author(s):  
Juan Han ◽  
Lu Zhu ◽  
Hai Fang ◽  
Jian Wang ◽  
Peng Wu
Keyword(s):  
Bearing Capacity ◽  
Energy Absorption ◽  
Sandwich Structure ◽  
Ultimate Load ◽  
Sandwich Structures ◽  
Elastic Displacement ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Composite Sandwich ◽  
Composite Sandwich Structures

Abstract This article proposed an innovative composite sandwich structure reinforced with trapezoidal latticed webs with angles of 45°, 60° and 75°. Four specimens were conducted according to quasi-static compression methods to investigate the compressive behavior of the novel composite structures. The experimental results indicated that the specimen with 45° trapezoidal latticed webs showed the most excellent energy absorption ability, which was about 2.5 times of the structures with vertical latticed webs. Compared to the traditional composite sandwich structure, the elastic displacement and ultimate load-bearing capacity of the specimen with 45° trapezoidal latticed webs were increased by 624.1 and 439.8%, respectively. Numerical analysis of the composite sandwich structures was carried out by using a nonlinear explicit finite element (FE) software ANSYS/LS-DYNA. The influence of the thickness of face sheets, lattice webs and foam density on the elastic ultimate load-bearing capacity, the elastic displacement and initial stiffness was analyzed. This innovative composite bumper device for bridge pier protection against ship collision was simulated to verify its performance. The results showed that the peak impact force of the composite anti-collision device with 45° trapezoidal latticed webs would be reduced by 17.3%, and the time duration will be prolonged by about 31.1%.

scholarly journals Constructing a biomimetic robust bi-layered hydrophilic lubrication coating on surface of silicone elastomer

Friction ◽  
2021 ◽  
Author(s):  
Luyao Gao ◽  
Xiaoduo Zhao ◽  
Shuanhong Ma ◽  
Zhengfeng Ma ◽  
Meirong Cai ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Composite Layer ◽  
High Load ◽  
Silicone Elastomer ◽  
Aqueous Lubrication ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Lubrication Performance ◽  
Wide Range

AbstractSilicone elastomers-based materials have been extensively involved in the field of biomedical devices, while their use is extremely restricted due to the poor surface lubricity and inherent hydrophobicity. This paper describes a novel strategy for generating a robust layered soft matter lubrication coating on the surface of the polydimethylsiloxane (PDMS) silicone elastomer, by entangling thick polyzwitterionic polyelectrolyte brush of poly (sulfobetaine methacrylate) (PSBMA) into the sub-surface of the initiator-embedded stiff hydrogel coating layer of P(AAm-co-AA-co-HEMA-Br)/Fe, to achieve a unified low friction and high load-bearing properties. Meanwhile, the stiff hydrogel layer with controllable thickness is covalently anchored on the surface of PDMS by adding iron powder to provide catalytic sites through surface catalytically initiated radical polymerization (SCIRP) method and provides high load-bearing capacity, while the topmost brush/hydrogel composite layer is highly effective for aqueous lubrication. Their synergy effects are capable of attaining low friction coefficient (COFs) under wide range of loaded condition in water environment with steel ball as sliding pair. Furthermore, the influence of mechanical modulus of the stiff hydrogel layer on the lubrication performance of layered coating is investigated, for which the COF is the lowest only when the modulus of the stiff hydrogel layer well matches the PDMS substrate. Surprisingly, the COF of the modified PDMS could remain low friction (COF < 0.05) stably after encountering 50,000 sliding cycles under 10 N load. Finally, the surface wear characterizations prove the robustness of the layered lubricating coating. This work provides a new route for engineering lubricious silicon elastomer with low friction, high load-bearing capacity, and considerable durability.

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