Hormigón y Acero

Letter from the director

2025-08-26T08:15:27+00:00

At the proposal of the previous director of the journal Gonzalo Ruiz, the Council of the Association of Structural Engineering ACHE appointed me as new director of Hormigón y Acero journal at its meeting at the end of April 2025.

I take on this challenge with enthusiasm to continue the excellent work carried out by the Editorial Board chaired by the last two directors, Luis Ortega Basagoiti and Gonzalo Ruiz.

ACHE's Hormigón y Acero journal will publish articles in English or Spanish on structures, including research, studies and projects on building and civil works. Topics will cover the design, construction, maintenance, repair, strengthening and demolition of structures. The publication will combine ordinary issues with monographic ones.

In the coming months, a monographic issue on the renovation of the Santiago Bernabéu stadium of the Real Madrid football club and another in honour of professors Hugo Corres and Toni Marí are expected to be published. Work is also being done on the preparation of a monographic issue on explosive actions in structures and another one dedicated to Jörg Schlaich.

Likewise, the publication of articles derived from the numerous and relevant papers presented at the ACHE congress, held in Granada at the end of June, will be encouraged. The abstracts of these presentations have been published by Hormigón y Acero in June 2025.

For all this work, I will have the support of the Editorial Committee for the day-to-day work that will collaborate with the Editor-in-Chief. I also have the support of the Editorial Board that will be renewed after the summer and that will address strategic subjects for the journal such as the achievement of quality articles to be published, the dissemination and internationalization of the journal and the improvement of its impact factors, among others. Later, the role of the journal's Scientific Advisory Board will also be analysed and strengthened.

This ordinary issue No. 306 of the journal, corresponding to the period May-August 2025, includes nine articles, five in English and four in Spanish. The first one is dealing with the demolition of the damaged deck of a bridge and its replacement with a new one in a high-density traffic road junction near the city of Madrid. The other eight articles cover studies on bridges and structures.

Finally, I am inviting authors of future articles on structures to consider Hormigón y Acero journal as an appropriate one for their publications, either in English or in Spanish, being the web www.hormigonyacero.com where all published articles till now can be downloaded for free.

Replacement of the deck and rehabilitation of the viaduct at the link between M-40 and M-607 in Madrid (Spain)

2025-08-26T08:02:52+00:00

The existing concrete viaduct 560 m long at the link between M-40 ring road and M-607 expressway in Madrid (Spain) was subjected to a very comprehensive process of evaluation and testing after high deck deflections and surface cracking were detected. As conclusion of these studies very severe damages and a process of concrete degradations were confirmed which led to the decision of dismounting the existing deck structure and constructing a new one supported on the existing substructure which had to be repaired and reinforced. Grupo Puentes has carried out both the process of deck disassembly and the construction of the new deck in a record time of approximately nine months. The viaduct is in a very traffic congested link to approach Madrid and crosses over not only the main roads, M-40 ring road and M-607 expressway, but also two approach ramps and two railway lines, one of them high-speed line.

Critical Discussion on the Performance of Underslung Movable Scaffolding Systems Strengthened With an Active Prestressing System

2025-08-26T08:02:52+00:00

The use of Movable Scaffolding Systems (MSSs) has proven to be an efficient and competitive construction method for in-situ prestressed concrete bridge decks. Among them, underslung MSSs are commonly used for spans up to 60 m, but the integration of active external prestressing systems has recently enabled their application to spans of up to 70 m. However, the effectiveness of these active systems is highly dependent on several design situations, and their benefits are not uniformly applicable across all construction stages. This paper examines the design optimization of MSSs with and without active prestressing system, evaluating their structural and economic implications. A detailed comparison is provided to assess the practical advantages and limitations of active prestressing systems, considering key influencing factors such as the construction sequence and operational constraints. Finally, the paper offers insights into the advantages and drawbacks of these systems in various bridge construction contexts.

Influence of Deep Foundations in a Deck Slab High-Speed Railway Bridge: A Theoretical Study

2025-08-26T08:02:52+00:00

In this research we discuss the importance of properly modeling the infrastructure of high-speed railway bridges with deep foundations when using the finite element method (FEM). To do so, we compared an isolated deck and several complete models with different characteristics. Parameters such as the length of the piles, the stiffness of the supporting layers and the type of dynamic load (10 different trains) were explored. This study started with the analysis of various parameters that determine the behavior of deep foundations with piles in simplified models. Based on these findings, we built a complete model. This research shows the importance of including not only the surrounding terrain but also the main substructure (i.e., piers and abutments) in the model. Recommendations on the amount of soil to include, its mechanical properties and the length of the piles needed are also provided to ensure the reliability of results when considering the soil-structure dynamic interaction. With this research, we intend to contribute to current knowledge with a series of guidelines and tools to help structural engineers in dynamic simulations through a theoretical case study.

Analytical Approach for Serviceability Assessment of Prestressed Concrete Girders Consisting of a Precast Beam and a Cast-in-place Slab

2025-08-26T08:02:53+00:00

This paper is focused on the assessment of the Serviceability Limit State of bridge girder cross-sections consisting of a precast, prestressed concrete beam and a cast-in-place top slab, which will be referred to as composite concrete sections because of the presence of more than one concrete within the section. Various methodologies for non-composite (i.e., with only one concrete within the section) concrete sections have been proposed by different authors to address the issue of stress assessment and crack control, mostly making use of analytical neutralization methods. In the present study, the neutralization method is extended and adapted to composite sections involving two concretes cast at different times. The proposed method is validated by comparison with a direct calculation method and commercial software. Three scenarios have been analyzed in the paper: midspan sections subjected to positive bending with cracking of the precast beam, sections at support regions of bridge girders subjected to negative bending in which the top slab is uncracked under permanent loads but undergoes cracking with the application of live loads, and sections at support regions in which the top slab is already cracked under permanent loads. Additionally, worked examples from real projects are provided.

The Impact of Steel Fiber Length and Dosage on Microstructure and Mechanical Performance in UHPFRC: A Hybrid Approach.

2025-08-26T08:02:53+00:00

This study evaluates the effects of steel fiber length (6 and 13 mm) and dosage on the microstructural and mechanical properties of an ultra-high-performance fiber-reinforced concrete (UHPFRC). The incorporation of 6 mm fiber significantly improved the material's workability characteristics. Microscopic evidence indicates better alignment and distribution of 13 mm fibers within the concrete matrix compared to 6 mm fibers, resulting in reduced porosity and enhanced matrix-fiber interaction. Mechanical testing confirmed that the inclusion of 13 mm steel fibers at various dosages consistently outperformed 6 mm fibers in enhancing compressive and flexural strengths. The optimal dosage, among those tested, for compressive strength was found to be 196 kg/m³ with 13 mm fibers, while the best performance in flexural strength was observed at 226 kg/m³. To address the complex casting challenges inherent in UHPFRC—specifically the intricate metallic fiber distribution and limited workability prompted a comprehensive investigation into fiber mixture optimization strategies. Hybrid fiber approach was explored by substituting 10%, 20%, and 30% of the 13 mm fiber dosage (196 kg/m³) with 6 mm steel fibers. Among these, the mix containing 80% of 13 mm steel fibers and 20% of 6 mm steel fibers demonstrated the highest flexural strength, even than those with higher steel fiber content (226 kg/m³). This hybridization suggests an optimized combination of fiber lengths for enhanced flexural performance without compromising compressive strength, providing insights into effective fiber-reinforcement strategies for UHPFRC applications.

Analytical Formulation for the Calculation of Bi-Girder Decks with Eccentric Loading

2025-08-26T08:02:54+00:00

An analytical approach is presented for obtain of the deformations and stresses of twin beam decks, widely used with channel-shaped precast beams. It is inspired and founded by the power of the strength function decomposition on more simple cases, and providing a mathematical formulation that leads the problem. This has been done according to outstanding work from Javier Manterola's “The open and closed section under eccentric loads” [1]. For the resolution, an approach to the mathematical formalism of Green's functions will be made. This analysis requires a set of admissible simplifications that approximate the solution fairly rigorously, and allow the direct evaluation of the action of moving loads. Finally, an analysis is carried out of the effectiveness of the transversal distribution achieved with various support conditions.

Reinforced short columns designed in accordance witht the regulations fib Model Code 2020 Eurocode 2:2023 and ABNT NBR 6118:2023. Sustainability study

2025-08-26T08:02:54+00:00

This paper aims to present a study of sustainability, focused on the design of short reinforced concrete columns respecting the premises of four established technical standards: ABNT NBR 6118:2014, ABNT NBR 6118:2023, fib Model Code 2020 (final draft) and Eurocode 2:2023. For the design of the columns, two reinforcement ratios were considered, one minimum (³ 0,4%) and one maximum for bypass splices (< 4,0%); two different concrete strength classes, C20 and C50; and, with f_ck referred to three different ages of 28, 56 and 91 days. This scenario provided 16 different possibilities for column configurations. Concrete was also considered to be mixed with two different cements: CR with high clinker content (> 90%) and CS with about 30% clinker. The comparative analysis addressed the topic of sustainability, considering only CO_2eq. emissions, and dematerialization. Under the conditions of this study, it is concluded that using Eurocode 2 (EN 1992-1-1) criteria, concrete produced with cements class CS and f_ck referenced at 56 days, always lead major dematerialization and lower greenhouse gas emissions. This study also demonstrates that design decisions, with smart concrete technology, can significantly influence the sustainability of one structure.

The Sensitivity of Anchorage Length to Splitting Failure in the New Eurocode 2

2025-08-26T08:02:54+00:00

In the new Eurocode 2 [1], the calculation of anchorage length has been notably modified compared to the previous version. The new formulation is significantly more sensitive to concrete splitting failure. In the previous version, the anchorage length could fluctuate by up to 30% due to effects such as splitting, reinforcement confinement, and lateral pressure. However, in the new Eurocode 2, due to the concrete splitting effect caused by the proximity of bars to each other or to edges, the anchorage length can increase by up to three times. Additionally, considering the effect of transverse reinforcement confinement can lead to considerable reductions in this length. Various graphical representations and examples are provided to quantify the sensitivity to splitting in the new formulation

Stiffness Matrix for Structures With Bars of Variable Section or Rigidity

2025-08-26T08:02:54+00:00

The matrix calculation by the Rigidity Matrix Method of structures composed of straight bars is normally carried out considering the bars of constant section and inertia and this hypothesis is considered sufficiently safe in all cases.

However, in practice, many structural systems are made up of bars of variable section or inertia, such as haunched bars, cracked reinforced concrete bars, steel bars with semi-rigid joints or mixed concrete and steel bars.

In this study, the Stiffness Matrix of a straight bar of variable section or inertia is proposed, whose rigidity coefficients are a function of the laws of variation of the area of its section, its Torsion Module and the Moments of Inertia referred to the axes normal to its guideline.

This approach does not increase the number of nodes in the structure or the number of unknowns in the matrix equation and allows, by establishing sufficiently approximate criteria for the calculation of its rigidity coefficients, to determine a more realistic behavior of its structural elements.