Each of the walkways is formed by the twinning of two planes: a vertical one, 0.80 m thick, with a 32x5 m gap for traffic passage under the structure and another horizontal one 7.30 m wide, with a stepped section, with a maximum depth of 0.42 m and a minimum of 0.14 m.

This results in a structural section consisting of an inverted “T” with a total depth of 1.42 m whose 0.80 m wide central rib emerges 1 m above the slab; This allows the level of the slab to be lowered and consequently the difference in level to be overcome by the flights of stairs. The walkway lintel was post-tensioned using three 0.6-inch 31-strand tendons of type 270k superstabilized steel that were tensioned to an initial force of 660 T each. For reasons of space, one of the anchors was left visible, although curiously protected.

The loads are transferred from the cantilevers by transverse bending to the central concrete rib, which flexes longitudinally and transfers the loads to the supports. Taking into account the reduced area of ​​the central nerve, a hyperstatic structural scheme was proposed composed of a board with a built-in support on the Plaza España side and another simply supported on the side of the Magic Fountain.

In this way, the stresses in the span and its deformation were reduced. However, the compression to which the central rib of the section was subjected was still very important, so it was decided to use high-resistance concrete, HP-80, as well as the aforementioned prestressing system, the design of which was highly conditioned by the narrow width of the rib, which limited the number of tendons.

The simple support was designed by embedding the walkway into a concrete partition that, due to its thinness, ensured sufficient flexibility. On the other hand, the embedded support was achieved by extending the spans of the walkways by 4 meters along the vertical concrete wall, thus ensuring the transfer of the compressions generated by the moment of embedding to the foundation. The concrete wall, 20 meters long, also served to anchor the access stairs to the walkway.

Structurally, it behaves like a deep beam.

Since high-strength concrete is a very poorly ductile material, it was required that the structure, under the Ultimate Limit State, have ductile behavior. Specifically, it was necessary for the section in the embedment to be more ductile than the section in the span since this is subject to greater stresses. The inverted T section ensures great ductility of the embedded support since at this point there is a large compression head, formed by the cantilevers and the lower part of the rib, which allows the structure to break ductilely due to the exhaustion of the active and passive reinforcement.

An important factor to take into account is the redistribution of moments from the embedment section to the span section; which in the case of the inverted T section is very low. The influence of the effects of temperature gradients, creep, shrinkage and possible differential settlements is also key. Thanks to the ductility of the embedment these effects can be neglected.

Finally, it should be said that in the Service Limit State the operation of the prestressing would be more efficient if the section were in a T and not in an inverted T since the eccentricity of the cables in the span would be much greater, increasing the difference between the isostatic and the hyperstatic moment. However, the ELU behavior of walkways with a T-section is much worse, since they would break brittlely (the large compression head would be in the opening and not in the embedment), in addition to having functional drawbacks (the clearance would be reduced, the rib would be visible from the street, etc.).

• - Post-tensioned concrete.

• - Prestressed structure.

• - Concrete.

• - Beam bridge.

• - Pedestrian bridge.

• - Avenida de la Reina María Cristina.

• - BELLOD, Juan Luis; AGUADO, Antonio; OLIVEIRA, Marcel; FERNANDEZ, Miguel Ángel; RUI-WAMBA, Javier Use of high resistance concrete. Montjuïc pedestrian walkways. Concrete and Steel, Number 194. College of Roads, Canals and Ports (1994).

• - Montjuïc pedestrian walkways. Link to the ESTEYCO website.

• - High-strength concrete in civil engineering Archived February 19, 2017 at the Wayback Machine. Link to ROP magazine.

• - Brief account of the ancient history of Barcelona that highlights the importance of its infrastructure in the evolution of the city Archived on February 20, 2017 in the Wayback Machine.. Link to the Royal Academy of Engineering.

• - CEDEX materials. Link to the CEDEX website.

• - Use of high resistance concrete. Montjuïc pedestrian walkways. Link to the magazine Hormigón y Acero nº194.

Each of the walkways is formed by the twinning of two planes: a vertical one, 0.80 m thick, with a 32x5 m gap for traffic passage under the structure and another horizontal one 7.30 m wide, with a stepped section, with a maximum depth of 0.42 m and a minimum of 0.14 m.

This results in a structural section consisting of an inverted “T” with a total depth of 1.42 m whose 0.80 m wide central rib emerges 1 m above the slab; This allows the level of the slab to be lowered and consequently the difference in level to be overcome by the flights of stairs. The walkway lintel was post-tensioned using three 0.6-inch 31-strand tendons of type 270k superstabilized steel that were tensioned to an initial force of 660 T each. For reasons of space, one of the anchors was left visible, although curiously protected.

The loads are transferred from the cantilevers by transverse bending to the central concrete rib, which flexes longitudinally and transfers the loads to the supports. Taking into account the reduced area of ​​the central nerve, a hyperstatic structural scheme was proposed composed of a board with a built-in support on the Plaza España side and another simply supported on the side of the Magic Fountain.

In this way, the stresses in the span and its deformation were reduced. However, the compression to which the central rib of the section was subjected was still very important, so it was decided to use high-resistance concrete, HP-80, as well as the aforementioned prestressing system, the design of which was highly conditioned by the narrow width of the rib, which limited the number of tendons.

The simple support was designed by embedding the walkway into a concrete partition that, due to its thinness, ensured sufficient flexibility. On the other hand, the embedded support was achieved by extending the spans of the walkways by 4 meters along the vertical concrete wall, thus ensuring the transfer of the compressions generated by the moment of embedding to the foundation. The concrete wall, 20 meters long, also served to anchor the access stairs to the walkway.

Structurally, it behaves like a deep beam.

Since high-strength concrete is a very poorly ductile material, it was required that the structure, under the Ultimate Limit State, have ductile behavior. Specifically, it was necessary for the section in the embedment to be more ductile than the section in the span since this is subject to greater stresses. The inverted T section ensures great ductility of the embedded support since at this point there is a large compression head, formed by the cantilevers and the lower part of the rib, which allows the structure to break ductilely due to the exhaustion of the active and passive reinforcement.

An important factor to take into account is the redistribution of moments from the embedment section to the span section; which in the case of the inverted T section is very low. The influence of the effects of temperature gradients, creep, shrinkage and possible differential settlements is also key. Thanks to the ductility of the embedment these effects can be neglected.

Finally, it should be said that in the Service Limit State the operation of the prestressing would be more efficient if the section were in a T and not in an inverted T since the eccentricity of the cables in the span would be much greater, increasing the difference between the isostatic and the hyperstatic moment. However, the ELU behavior of walkways with a T-section is much worse, since they would break brittlely (the large compression head would be in the opening and not in the embedment), in addition to having functional drawbacks (the clearance would be reduced, the rib would be visible from the street, etc.).

• - Post-tensioned concrete.

• - Prestressed structure.

• - Concrete.

• - Beam bridge.

• - Pedestrian bridge.

• - Avenida de la Reina María Cristina.

• - BELLOD, Juan Luis; AGUADO, Antonio; OLIVEIRA, Marcel; FERNANDEZ, Miguel Ángel; RUI-WAMBA, Javier Use of high resistance concrete. Montjuïc pedestrian walkways. Concrete and Steel, Number 194. College of Roads, Canals and Ports (1994).

• - Montjuïc pedestrian walkways. Link to the ESTEYCO website.

• - High-strength concrete in civil engineering Archived February 19, 2017 at the Wayback Machine. Link to ROP magazine.

• - Brief account of the ancient history of Barcelona that highlights the importance of its infrastructure in the evolution of the city Archived on February 20, 2017 in the Wayback Machine.. Link to the Royal Academy of Engineering.

• - CEDEX materials. Link to the CEDEX website.

• - Use of high resistance concrete. Montjuïc pedestrian walkways. Link to the magazine Hormigón y Acero nº194.