Experimental study on mechanical behavior of orthotropic steel deck with adhesively bonded rigid pavement

The steel deck with rigid pavement has a lower risk of fatigue failure owing to the enhanced local rigidity. A reliable connection of steel plate and pavement and a convenient construction are critical concerns for this deck type. To seek a new application meeting the aforementioned requirements, this paper proposed a steel deck with adhesively bonded rigid pavement cast by non-reinforced ultra-high performance concrete (UHPC). To study the constructability and flexural properties of this deck type in a bridge deck system, four specimens including two with adhesively bonded connection and two reference ones with shear stud connection were fabricated and experimentally investigated by positive and negative bending tests. In addition, a simplified pretreatment of steel substrate was conducted before the application of epoxy resin to simulate the low quality of on-site construction. Experimental results indicate that the shear strength of the bonding connection with simplified steel pretreatment could decrease to half of that with strict preparation. Bending tests demonstrate that the adhesive bonding provides a more rigid connection between steel and concrete than shear studs did. The bonding failure load was 1.5 times the U-rib yielding load, indicating a high positive bending-carrying capacity of the deck. The adhesive provides better crack resistance than shear studs in negative bending. From a perspective on the bending behavior in the deck system, the adhesive bonding was reliable to obtain high bending capacities to resist actual vehicle loads. Besides, the non-uniform shrinkage of non-reinforced UHPC pavement can cause a 30% reduction of cracking strength.

Optimum design of a composite floor system considering environmental and economic impacts

The composite floor system, composed of steel deck and concrete slab, generates more efficient and economical structures. On the other hand, the design of this type of structure has a high complexity level due to the consideration of several variables. In this respect, the objective of this paper is to present the formulation of the optimization problem for a composite floor system (steel and concrete) considering such environmental as economic impacts. To formulate the optimization problem, the reduction of environmental impact was adopted as an objective function - assuming the CO2 emission and the finance cost as parameters. The restrictions were taken by the limiting states imposed in standard NBR 8800:2008. The computer program was developed via Matlab R2016a and the optimization process was carried out using the Genetic Algorithm toolbox existing in this platform. Two application examples of the formulation at hand are presented: the first from the literature and the second from an existing building - in both situations the influences of different concrete compressive characteristic strengths were analyzed. The results of the optimization problem show a reduction in geometry and, consequently, in its weight. The solution found by the program reduces by up to 17.70% of CO2 emissions and 17.47% of the finance cost. When was applying different concrete compressive strengths, the optimal solution for environmental impact did not get the lowest cost. In general, the steel deck formwork obtained the highest percentage of environmental impact, while the beams and girders, with the same shape configuration, had the highest finance cost. Therefore, it is shown that the optimal design solution to CO2 emissions is not always the better solution for the finance cost.

COMPARACIÓN TÉCNICO-ECONÓMICA DEL COMPORTAMIENTO A LA CONTRACCIÓN Y TEMPERATURA DEL HORMIGÓN DE LOSAS TIPO DECK, UTILIZANDO FIBRAS DE ACERO VS. MALLA DE ACERO ELECTROSOLDADA

RESUMEN Esta investigación consiste en determinar qué tan efectivo podría resultar el reemplazo del acero de refuerzo con malla electrosoldada, utilizada convencionalmente losas con placa colaborante (steel deck), por fibras de acero Dramix®, para el control de fisuras en la superficie del hormigón. Se evaluó el comportamiento de ambas opciones, frente a la contracción y dilatación que se produce, debido a agentes externos de temperatura, humedad y viento, con la finalidad de determinar el sistema más eficiente en términos económicos, técnicos y constructivos. Para la comparación técnica se utilizó la normativa de ensayo ASTM C1579; para la comparación económica se realizó el análisis de precios unitarios APU en ambos casos. La determinación de la eficiencia constructiva se la evaluó a partir de referencias bibliográficas. Para el análisis técnico, se utilizaron normativas de ensayo complementarias, para determinar las propiedades mecánicas de los materiales, normativa ASTM; y para la dosificación del hormigón, normativa ACI. Los resultados obtenidos son lo siguientes: en cuánto al análisis técnico, la fisuración en las losetas de hormigón, reforzadas con fibras de acero, se redujo en un rango del 21% al 29% frente a aquellas que fueron reforzadas con malla electrosoldada; el análisis económico, en el primer caso, resultó en un ahorro aproximado del 1.4% del costo con respecto al segundo; el análisis constructivo demuestra que, también se obtuvieron resultados positivos en el caso del hormigón con fibras de acero, debido a reducción en rubros, tiempos, logística y riesgos laborales. Se concluyó así que, en los tres casos, las fibras de acero tienen mayores ventajas, para los fenómenos estudiados, frente a la malla de acero electrosoldada. Se concluyó también que, cualquier método de refuerzo de losas con placa colaborante, así como un buen acabado superficial y un correcto curado del hormigón, son necesario para reducir la fisuración en estas.

Response analysis of orthotropic steel deck pavement based on interlayer contact bonding condition

In this research the interlayer contact condition was considered between the adjacent layers of orthotropic steel deck pavement, and an interface contact bonding model was applied to simulate the interlayer bonding condition and evaluate the response of deck pavement under vehicle loads. An advantage of this model is that it can simulate not only the full-bond condition but also the debonding condition at somewhere between adjacent layers. The responses of the orthotropic steel deck pavement were calculated and analyzed by the model, and it found that this model is reasonable and credible to evaluate the responses of the deck pavement comparing with the previous researches. The full-bond condition was an ideal condition between adjacent layers, which was prone to underestimate the responses and deformation of the deck pavement. Moreover, the position and size of the disengaging area have a notable influence on the tensile strain at the top of SMA layer and the bottom of GA layer, and the tensile strain of them also increase with the increase of the disengaging area. Finally, the responses of the steel deck pavement changed obviously when the vehicle speed increase, so the suitable speed limit may reduce the responses and deformation for prolonging the service life of the orthotropic steel deck pavement.

Flexural Behaviors of Precast Reinforced Concrete -EPSfoam-Steel Deck Hybrid Panel

This paper presented the flexural behavior of the newly developed hybrid panel which included the comparison of the ultimate load, load-deflection behavior, and failure modes. The experimental study was carried out on precast reinforced concrete-EPSfoam-steel deck hybrid panels (CES)� consist of three layers of material : concrete� layer is on the top, the steel deck is located on the bottom layer, and the EPS foam layer as the core. The dimensions of CES are 300 mm x 1200 mm with thickness of concrete layer and EPS foam as variables. The concrete thick were 30 mm and 40mm. The density of EPS foam was 12 kg/m3, 20 kg/m3, and 30 kg/m3. The static flexural test of CES was conducted in accordance with the ASTM C 393-00 standard for determination of flexural strength on concrete, the load was applied at third-point loading. This test was carried out with monotonic static load, deflection control using a loading frame with capacity of 10 kN. The results show that increase the thickness of the concrete layer from 30mm to 40mm with� EPSfoam density of 12 kg /m3, 20 kg/m3, and 30 kg/m3 achieved a maximum load increase of 33.51%; 46,13%; and 37.35%, respectively.

A comparative study of several nature-inspired algorithms in steel deck floor system cost optimization

Steel deck floor systems can be considered as one of the main components of a structure. As technology advances, the role of optimization is used in many aspects of structural designs. Steel deck floor systems are one of many components that are usually optimized to look for its optimum cost but are still able to hold the structure. This study compares the performance of the particle swarm optimization (PSO), artificial bee colony (ABC), differential evolution (DE), and symbiotic organisms search (SOS), that categorized as nature-inspired algorithms, in the optimization of a steel deck floor system. The variables considered are the edge beams, interior beams, and the composite steel deck. The results show that the SOS gives the most optimum cost with a better average and a perfect success rate.