scholarly journals Propiedades del hormigón reciclado para el uso como soleras de hormigón en pavimentos industriales=Properties of recycled concrete to use as concrete slabs in industrial pavements

2018 ◽  
Vol 4 (2) ◽  
pp. 25
Author(s):  
M.A. Morales ◽  
J.A. Pérez ◽  
M. Del Rio ◽  
J.C. Sánchez ◽  
J. Casbas ◽  
...  

Resumen El presente estudio analiza el estado tensional de distintas placas delgadas apoyadas sobre terreno elástico empleando modelos de elementos finitos para distintos tipos de hormigones reciclados y de primer uso, distintos valores de las cargas y de las condiciones de apoyo del terreno, concluyendo que las tensiones que se obtienen en hormigones reciclados son aproximadamente un 4,5% menores que en hormigones fabricados con áridos de primer uso, en cualquiera de los casos analizados. Con los datos obtenidos para las tensiones, se han elaborado gráficas de dimensionamiento del espesor mínimo necesario en Estado Límite Último de flexión. Estas gráficas muestran menores espesores necesarios en el caso de hormigones reciclados, si bien las reducciones posibles no superan los 0,5 cm para las cargas analizadas. Otro aspecto a tener en cuenta es que, dado que el proceso de agotamiento por fatiga en el hormigón depende fundamentalmente de la máxima tensión alcanzada en el hormigón respecto de su capacidad resistente y no solo de la oscilación de tensiones, el hormigón reciclado permite alargar la vida útil de la estructura. Abstract The present study analyzes the tensional state of different thin plates supported on elastic terrain using finite element models for different types of recycled and first-use concretes, different values of loads and ground support conditions, concluding that the tensions that are obtained in recycled concretes are approximately 4.5% lower than in concrete made with aggregates of first use, in any of the cases analyzed. With the data obtained for the tensions, graphs of sizing of the minimum thickness necessary in Ultimate Limit State of flexion have been drawn up. These graphs show lower thicknesses required in the case of recycled concretes, although the possible reductions do not exceed 0.5 cm for the loads analyzed. Another aspect to be taken into account is that, given that the fatigue depletion process in concrete depends mainly on the maximum tension reached in the concrete with respect to its resistant capacity and not only the tension oscillation, the recycled concrete allows to extend the useful life of the structure.

2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Niall Holmes ◽  
Eoin Byrne

This paper investigates the effect of improper posttensioning of a 2-way spanning concrete slab subject to a central point load. Due to plate slippage alone, the support conditions only offered a 1-way spanning action which could have led to premature failure with dangerous consequences. Posttensioning can strengthen a flat slab against punching shear by controlling deflections and cracking under service loads compared with traditional punching shear reinforcing methods leading to more slender structures and economic solutions for longer spans. However, if the method is not properly applied, these thinner floor plates can fail in a brittle and sudden manner by punching at ultimate limit state and excessive deflection in serviceability. Concrete slabs containing traditional shear reinforcement performed adequately and demonstrated that the critical punching shear perimeter, defined as twice the depth of the slab, was confirmed from measured deflections and crack pattern analysis.


2015 ◽  
Vol 752-753 ◽  
pp. 711-714 ◽  
Author(s):  
Josef Musílek ◽  
Karel Kubečka

The paper deals with load-carrying capacity of bolted connections subjected to unequal double shears with thin plates as outer members and inner timber member. There are derived equations which describe the load-carrying capacity of this connection type in the ultimate limit state.


2015 ◽  
Vol 749 ◽  
pp. 368-372
Author(s):  
Jana Vaskova ◽  
Pavlina Matečková

The subject of this paper is an universal software for reinforced concrete annular and circular slabs reinforced in the radial and tangential direction. Such slabs are used for roof and ceiling structures of buildings. The software can be used for design and assessment of rotationally symmetrically loaded annular and circular reinforced concrete slabs with arbitrary supports and span. Based on user's choice, the software proposes solutions to not only meet all the design principles, but especially ultimate limit state and serviceability limit state.


2015 ◽  
Vol 752-753 ◽  
pp. 652-655 ◽  
Author(s):  
Josef Musílek ◽  
Karel Kubečka

The paper deals with reliability in ultimate limit state of timber structure bolted connections subjected to unequal double shear with thin plates as outer members and inner timber member. There are derived equations for calculation of the reliability of this connection type in the ultimate limit state.


Author(s):  
Ю. Г. Москалькова ◽  
С. В. Данилов ◽  
В. А. Ржевуцкая

Постановка задачи. Исследуется метод усиления железобетонных колонн устройством стальной обоймы с обетонированием, который позволяет восстанавливать эксплуатационные показатели колонн, имеющих значительные дефекты и повреждения. Предпосылкой настоящих исследований явилось предположение о том, что усиление стальной обоймой с обетонированием является эффективным способом повышения несущей способности железобетонных колонн, причем вариант приложения нагрузки - только на бетонное ядро или ко всему сечению - существенно на эффективность усиления не влияет. В связи с этим целью исследования является определение необходимости устройства стального оголовка и включения в работу ветвей стальной обоймы при условии обетонирования стержня колонны по всей высоте. Результаты и выводы. Рациональным признан способ передачи нагрузки только на бетонное ядро усиленных колонн, поскольку устройство оголовка стальной обоймы требует применения сложных конструктивно-технологических решений, но при этом дополнительно увеличивает несущую способность незначительно (согласно проведенным исследованиям менее чем на 10 %). Ввиду отсутствия необходимости устройства конструкций стального оголовка снижаются трудоемкость и сроки производства работ по усилению колонн. Statement of the problem. The method of strengthening reinforced concrete columns with a steel clipping and the concrete surfacing is investigated. This method allows one to repair the columns with significant defects and damage. The prerequisite for this study was the assumption of strengthening with a steel clipping and the concrete surfacing is an effective way to increase the ultimate limit state of reinforced concrete columns, furthermore, the option of applying the load (only to the concrete core or to the entire section) does not significantly affect the strengthening effectiveness. In this regard, the purpose of the investigation was to identify the need to include the steel jacketing in the work, on the condition the column is coated with concrete along with the entire height. Results and conclusions. The load transfer method only to the concrete core of the strengthened columns is recognized as rational since the device of the steel clipping head requires the use of complex structural and technological solutions, but at the same time additionally increases the ultimate limit state insignificantly (according to the studies by less than 10 %). Due to the absence of the need to establish structures of the steel jacketing head, the labor intensiveness and terms of work production on strengthening the columns are reduced.


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