Knowing the real dynamic properties of a structure, natural frequencies and vibration modes is essential to ensure comfort and safety for users, as well as predictability for maintenance of public equipment. With this objective in mind, two pedestrian footbridges on the São Paulo subway were monitored by IEME Brasil last March, which used Vibrodina, a mechanical device that makes the structure vibrate at a specific frequency range, in the dynamic forced vibration test.

“The precise determination of the structure’s natural frequency is extremely important for validating theoretical models and ensuring that it does not coincide with the excitation frequencies generated by pedestrian traffic. Avoiding resonance is essential to ensure user comfort and the structural integrity of the footbridge,” explains engineer Marco Juliani, director of IEME.

The footbridges are located at the Santo Amaro station of the São Paulo subway, which is shared by subway lines 5-Lilás (ViaMobilidade) and 9-Esmeralda, of CPTM. They are 111m long and 7.4m wide and are formed by a metal lattice structure with tubular profiles and a steel deck slab. The central span, which crosses the Pinheiros River, is approximately 80m long. The work is the responsibility of EGTC Infra.

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On November 29, in Brasília, BNDES announced a financial contribution of R$10.65 billion for infrastructure projects in São Paulo. The resources, which are part of the New PAC (Growth Acceleration Program), will be allocated to expansion projects for the São Paulo subway, a road complex, a modern rail link between the city of São Paulo and Campinas (about 100 km away), and the purchase of 1,300 electric buses.

Infrastructure projects and projects, especially in the road and metro-rail areas, are the main activity of IEME Brasil, which has been working for over 35 years with instrumentation and monitoring of roads, data processing and analysis for engineering reports, various tests, and accredited inspection (by INMETRO) of road and rail projects and projects. In addition, it has LAEDE, a laboratory that has Cgcre accreditation (ABNT NBR ISO/IEC 17025) and is part of the Brazilian Network of Testing Laboratories (RBLE).

Due to investments in infrastructure, which are already reflecting an increase in demand, LAEDE recently acquired new equipment (hydraulic pumps and controllers) for testing metro-rail components and systems. The hydraulic pump, for example, is a state-of-the-art piece of equipment, capable of saving up to 20% of energy, and is the first of its kind to be installed in Brazil.

The investments ratify IEME’s commitment to the quality and safety of the projects and works in which it participates, remembering that the company is present on all São Paulo subway lines and in the structural tests of Rodoanel Norte, to name a few examples. The company also carries out a series of works focused on land regularization and social housing.

IEME Brazil and LAEDE participated in the Quality Conference – From Compliance to Performance, an event held by ACCIONA, on Tuesday, November 19. The Spanish company is building Line 6 – Orange of the São Paulo subway, a 15.3 km project that will connect the current São Joaquim station, in the central neighborhood of Liberdade, to Pátio Morro Grande, in the northern part of São Paulo.

Line 6 is considered the largest infrastructure project currently under construction in South America and one of the main subway projects in the region. At the event, aimed at ACCIONA employees, Lucas Juliani, coordinator of LAEDE, gave a presentation about the company and explained some of the quality controls performed in the laboratory, which has among its main focuses precisely the safety and durability of subway systems.

Line 6 itself has had services performed by LAEDE. Recently, components of the superstructure of the permanent way (mass-spring system, sleepers, rail fastening, rail welds, among others) were tested.

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Learn more about LAEDE

The city of São Paulo hosted, between September 11 and 14, 2024, at São Paulo Expo, the first edition of the Construction Pathology Fair (FEIPAT), held by the Adpat Community of Construction Pathology. The inaugural edition brought together, in an exclusive 450 m², companies specializing in construction pathology, building maintenance and property management.

IEME Brazil invited engineers José Filipe Carvalho de Viveiros, Mikaella Ogata and Luciana Kneip Pereira to visit the fair and learn about new technologies and services related to structural pathology. “This was the first edition of FEIPAT, an important milestone for the sector, as it contributes to giving greater visibility and recognition to this niche”, says engineer José Filipe Carvalho de Viveiros.

In addition to the opportunity to meet new companies, the fair brought together several IEME partners, also committed to offering services and products focused on the safety, quality and durability of structures.

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Safety and optimization of preventive maintenance are priorities for IEME Brasil and LAEDE when it comes to evaluating their customers’ metro rail systems. To achieve this, the company relies on cutting-edge technologies and methodologies, the result of exchanges and monitoring of studies in some of the most advanced technological centers on the subject. One of the resources adopted by IEME for this purpose is the instrumented wheelset calibrator, studied in Italy by the Università degli Studi di Firenze, Sapienza in Rome and the Polytechnic of Milan, institutions visited by the company.

But what is the instrumented wheelset calibrator?

“The calibrator is a bench designed to apply existing loads on the permanent track onto an instrumented wheel set with the aim of correlating wheel-rail contact forces and deformations. To this end, electrical resistance strain gauges, hydraulic jacks, actuators and various load cells are used, in addition to a structure capable of supporting such loads”, explains engineer Tiago Juliani, Engineering coordinator at IEME Brasil.

There is a variety of information obtained by the calibrated instrumented wheelset. With the passage of the instrumented wheelset, the wheel-rail contact forces and the L/V relationship (lateral force / vertical force of the wheel) are obtained along the entire path of the train, which may indicate problems both on the permanent track as well as in the rolling stock, such as geometric imperfections in the track, welding defects, failures in railway components, poor maintenance of tracks and wheels, among others. Furthermore, the operational risk of the line is assessed with the L/V ratio.

Therefore, the calibrator is adopted whenever a new measurement campaign is carried out with the instrumented wheelset and, if the same previously instrumented wheelset is used, there has been a certain mileage between one campaign and another.

Versatility and security

Elastomers are polymeric materials with viscoelastic properties, which means they can be stretched and deformed under tension and then return to their original shape when the tension is removed. This unique ability makes these materials extremely versatile and valuable across multiple industries.

In the context of civil and railway construction, elastomers play a crucial role. They are used in large works and railway systems for a series of applications, ranging from shock absorption to vibration isolation. These properties are fundamental to ensuring the safety and adequate performance of structures and systems.

However, to ensure that these elastomers meet the necessary quality and performance standards, it is essential to carry out a series of rigorous tests defined by international Technical Standards. This is where LAEDE – Acoustics and Dynamic and Static Testing Laboratory comes in.

LAEDE, part of IEME Brasil, has extensive experience in high-capacity static and dynamic mechanical testing, which plays a key role in the evaluation and certification of elastomers used in a variety of applications.

The tests carried out by LAEDE include the evaluation of the mechanical and performance properties of materials. This includes quasi-static tests of vertical and shear stiffness, dynamic tests of free and forced vibration, permanent loading, fatigue (mechanical aging) and obtaining the damping coefficient. Additionally, the laboratory is capable of reproducing specific conditions in greenhouse and water environments, which is crucial for testing elastomers in real-world conditions.

The importance of these tests cannot be underestimated. They ensure that elastomers function as expected, providing the necessary shock absorption, vibration isolation and flexibility in various applications. This rigorous assessment also helps identify any wear or degradation over time, ensuring the safety and durability of these materials.

LAEDE is part of the Brazilian Network of Testing Laboratories (RBLE) and is a laboratory accredited by Cgcre in accordance with ABNT NBR ISO/IEC 17025. This means that the tests meet the highest standards of quality and technical competence. Therefore, when choosing LAEDE to carry out these tests, you can be confident that you are working with experienced and certified professionals.

See more on the LAEDE website.