Pushover is a nonlinear static procedure that incrementally applies lateral loads to a bridge model, typically until a target displacement is reached or the structure reaches global instability. The analysis is instrumental in identifying inelastic behavior, hinge formation, redistribution of internal forces, and the progression of failure mechanisms.

 

 

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What is Rail Structure Interaction?

 

Rail structure interaction studies the interaction between railway tracks and concrete bridge structures. Differential stresses are generated in the rail and the deck of a railway bridge due to temperature, braking, traction, and the train's weight. Let's take two cases here. One interacts with rail and ground, and the other shows an interaction of rail and bridge. So, the area of interest is the second case, not the first one. 

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The need for RSI in the modern world

Rail structure interaction (RSI) remains crucial in the rail transportation era and with the recent development of high-speed trains globally, playing a vital role in estimating the impact of rail on the bridge and the optimum design of the bridge system for the safe passage of trains without disturbing the passenger's riding comfort. Most of the modern-day railways use CWR. Fish plate joints were used in which the length of each rail was around 20-40 m, but in the case of CWR, the length of rails is up to a few hundred meters. The fish plates allow certain deflections, releasing the stresses in the rails, while accumulation of stress occurs in CWR.

Let's take two scenarios: rails over an embankment and a bridge.

Figure 1:a) Fish Plate Joint b) Welded Rail Joint

 

Case 1: Rails on the ground

Let’s take a scenario and study the stresses in railway tracks when there is no bridge, and increase the temperature. We know that the ground won’t react to this change in temperature, but the railway track tends to expand. In the central zone, we can observe that there will not be any net force acting, and the stress profile is constant here.

• Stress = E x alpha x T
• Alpha - coefficient thermal expansion
• T - temperature rise
• 
  Figure 2: Central zone

 

🕖 Surviving in times of change

 

I felt one thing while working as a structural engineer who designs concrete bridges(RC/PSC) according to various countries' design standards: A profound understanding of ACI318(AASHTO) and EN2 is essential to successfully working on bridge projects. Most countries' standards are developed based on those standards. (Of course, it is my personal opinion.) Personally, I believe that my design career was successful because I recognized these facts.

 

 Reviewing the ACI318 and EN once is not enough because design standards change over time. Revision is an indispensable process, and I expect two things before the new edition is released.

 

 First, to be precise, the existing vague parts; the other is simplifying the calculating equations to apply the practical design process. Fundamentally, those are relevant problems. Complexity usually brings unclear parts.

 Unfortunately, the newly updated 2G:Eurocode 2 did not meet these expectations. Standards are more convoluted than before, and this has indeed led to an increase in unclear areas.

 

 Now, the moment has come to prepare for the future.

 

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⚙️ Introduction to Our New Tool

 

Now, let's talk about tools.

The primary function of this tool is to easily output stress-strain curve graphs, which are strength characteristics of concrete, and graphs of time-dependent characteristics such as creep and drying shrinkage.

 Notably, by providing the existing EN1992-1-1 and the new 2G:EN1992-1-1 together, the user can compare those results and experience the calculating processes. I believe it would be a handy tool to validate that new standards align with user understanding before implementing them in practice.

 

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❓How to use it?

 

🔢 Input values

 

1. Select Graph

• Concrete Properties (Stress-strain diagrams)
• Time-Dependent Behavior

2. Select Standard Code

• 2G:EN 1992-1-1
• EN 1992-1-1

3. Put values

4. Click the calculation button

 

📈 Review a result

 

1. Select Graph type

• A. Concrete Properties
  • Non-linear
  • Parabola rectangle
  • Bi-linear (Not include 2G:EN 1992-1-1)

• B. Time-Dependent Behavior
  • Creep  coefficient
  • Shrinkage strain
  • Elastic modulus
  • Mean compressive strength
  • Mean tensile strength

2. View a result as a table

3. Check additional information

4. Graph tool (save, zoom in and out, move, restore)

 

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😜 Conclusion

 

The 2nd Generation Eurocode is continually being released and is targeted to start use in 2028. In line with this, MIDAS provides tools to compare the modifications between the 1st and 2nd generations. This work will only be possible with the support of ongoing research and constant user interest. We ask for your interest and anticipation for the upcoming tools.

 

 

 

Are you curious about this tool?

Click the link below to access MIDAS Tools for free.

Some people have already heard about the second generation of Eurocodes. It’s not too early to figure out what changes are in the second generation and what civil and architecture engineers need to know. This blog does not handle the specifications; however, it would be helpful for those who want to know the overall changes. I will give you a quick summary for busy people.

What is Application Programming Interface (API)?

 

The first thought that will come into your mind is exactly what is this API? and why a civil engineer like me needs to know about this techno-sounding topic.

Defining Suspension Bridges: An Engineering Marvel

Suspension bridges are remarkable structures supported by massive main cables stretched between two or more towers. This design is the preferred choice for expansive spans where conventional bridge types prove impractical. The main cables, anchored at both ends of the bridge, are under tension and bear the weight of the bridge deck along with dynamic loads from vehicles and pedestrians. Typically, the deck hangs below these main cables, secured by smaller vertical cables or rods.

 

Beam Bridges: An Essential Element in Transportation Infrastructure

Beam bridges, commonly referred to as girder bridges, represent one of the most prevalent and fundamental bridge types globally. Despite their apparent simplicity, these structures play a pivotal role in our transportation systems, ensuring the safe passage of vehicles and pedestrians across various terrains such as rivers, valleys, and highways. This article delves into the design, construction, and essential features of beam bridges, highlighting the science behind their stability and strength.

 

1. Introduction

When performing the Rail-Structure Interaction (RSI), It is often found that the stress limits are exceeding the permissible values. So there are some countermeasures to ensure safety. Let’s look at how we can implement these control measures which affect the stresses in rails when performing rail structure interaction.

1. Introduction

With the recent development of high-speed trains globally, structural interaction plays an important role in estimating the impact of rail on the bridge and the optimum design of the bridge system for the safe passage of trains without disturbing the passengers' riding comfort. The UIC 774-3, Eurocode in 1991-2, RDSO, Korean code, ACI, and various codes and standards provide methodologies for considering rail-bridge interaction problems in the design and analysis of railway bridges. These guidelines take into account the dynamic interactions between trains and bridges, which can affect the stress, displacement, and stability of the rail during train passage. Based on experimental and numerical studies, these guidelines provide limiting values for stress, displacement, and stability of the rail to ensure railway bridges' safe and reliable performance. These limiting values are derived to prevent excessive deformations and stress in the rail that could lead to failure of the rail or other bridge components.

1. Introduction

In Prestressed concrete structures, the prestressing force is a crucial variable type. The behaviors of pre-stressed concrete structures depend on the effective prestress because it provides compressive stresses to counteract the tensile stresses that develop in the concrete due to loads. However, the prestressing force does not remain constant over time due to various factors that cause prestress losses. These losses can occur during the transfer of prestress from the tendons to the concrete member or over the service life of the structure.

A. Introduction:

Differential shrinkage is a phenomenon that occurs in composite sections, which are made up of different materials or different grades of concrete, as the different materials will experience a different rate of shrinkage (i.e., PSC composite I Girder). In this article, we will focus on differential shrinkage due to the different time-dependent effects for the composite section consisting of the same material with different grades of concrete for the deck slab and the girder. Differential shrinkage is an important concept to consider when designing composite sections even when the same material is used for both the girder and deck, the age difference will cause the differential shrinkage effects. This will induce different time-dependent effects on both since both the parts are integrally connected internal stress will be generated to reduce the differential effect.

Eurocode VS BS code

 

A. Introduction

I'd like to share my old experience with the Tendon Profile.

A. Introduction

Designing a curved bridge was a challenge for me in every aspect. The tendon profile in MIDAS Civil, which we covered before, it’s a very well-known issue,

1. Introduction

In India, the IS codes, or Indian Standards codes, play a crucial role in ensuring the quality, safety, and reliability of structures in India. It serves as an essential benchmarks to guide the design, construction, modification, and upkeep of structures. These codes are formulated by the Bureau of Indian Standards (BIS), a national body that develops and publishes standards to promote quality and consistency across various industries. These codes are reviewed from time to time and updated to reflect the latest developments in industries.