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Nonlinear Analysis

Understand the different sources of nonlinearity, and how to control nonlinear analysis in LUSAS.

Who is it for?

This course is for engineers with a good understanding of linear analysis but who need to progress to nonlinear analysis for design and assessments.
In summary
- Understand why you need to move from linear to nonlinear analysis
- Appreciate the fundamentals of nonlinear control and how to obtain a converged solution
- Get an overview of the major sources of nonlinearity and how to set them up in LUSAS
- Learn from practical nonlinear examples including snap-through of a shallow arch, reinforced concrete frame taken to failure by cracking of concrete and yielding of reinforcement, a slab foundation subject to lift-off at its edge, and staged construction analysis.

Geometric nonlinearity (including large deflections)

How deformations affect the performance of a structure and its stability or buckling resilience

Nonlinear materials

Do stresses remain in the linear range? Or do you need to consider yielding, cracking, crushing etc?

Nonlinear boundary conditions and contact analysis

Considering when parts of a structure come in or out of contact with supports, or even with other parts of the structure

Staged construction

How to account for a staged construction process that locks in stresses from one stage, affecting later stages. Also considering time-dependent material effects.

Overview of nonlinear principles and how they are applied in LUSAS, with a focus on geometric nonlinearity.

Presentation on fundamentals of nonlinear analysis.
Investigation of how linear analysis can give inaccurate answers when geometric nonlinearity is relevant.
How to turn on nonlinear analysis, and control the optional settings to achieve results.
Demonstration examples:
1. Simple horizontal cable subjected to vertical load.
2. Snap-through of a shallow arch.
Homework example to be completed by delegates (snap-through arch)
Online quiz to complete the session.

Investigation of different nonlinear models where the stress-strain curves cease to be linear.

Presentation on elasto-plastic material behaviour, suitable for metals, soils and plastics, considering different yield criteria in 1D, 2D and 3D
Demonstration example: Steel rigging plate taken to ultimate capacity failure.
Presentation on brittle fracture material behaviour, suitable for concrete and masonry, using LUSAS's bespoke material model.
Discussion on further nonlinear concepts in LUSAS, such as manual vs automatic load incrementation, loading carried forward, and stresses and strains carried forward.
Demonstration example: Reinforced concrete portal frame taken to failure by cracking of concrete and yielding of reinforcement.
Homework examples to be completed by delegates (same as demonstration examples)
Online quiz to complete the session.

Consideration of when supports do not behave linearly (lift-off supports), and when structural elements come into or out of contact with each other.

Presentation on lift-off and contact support attributes.
Demonstration example: Factory gantry with lift-off / contact.
Presentation on element-to-element contact and lift-off, using joint elements or slideline attributes, and when to use each option.
Demonstration example: Slab on grade.
Homework examples to be completed by delegates (same as demonstration examples).
Online quiz to complete the session.

Overview of why staged construction is considered as nonlinear in LUSAS, and how geometric nonlinearity, material nonlinearity and boundary nonlinearity can all affect it.

Presentation on staged construction methods and the activation and deactivation facility
Investigation of how the stages of construction affect the build-up of forces and deflections in the structure can be locked-in, affecting final design
Consideration of different construction methodologies and how they can be modelled in LUSAS
Time dependent creep effects of concrete
Presentation examples
1. Ladder beam staged construction with temporary bracing.
2. Span-by-span deactivation control and support activation.
3. Staged construction of a two span beam with creep, starting as simply supported before being made continuous
Homework examples (ladder beam and two span beam with creep) to be completed by delegates.
Online quiz to complete the session.

Accessing LUSAS

Please note that this course has been prepared using version 23 of LUSAS. If using other versions, there may be minor differences.

Individuals who wish to attend the training who do not have access to the required version of the software may request a temporary training licence from LUSAS to allow the running of the software on their personal computers.

After booking your place on the course, please contact onlinetraining@lusas.com to request a licence stating your name and details as asked for on the booking form.

Andy Taylor is the Training Manager at LUSAS.

He is a Chartered Civil Engineer with 8 years of industry experience as a practising civil and structural engineer, working primarily on the design and analysis of bridges and other highway structures; plus 10 years at LUSAS in various roles, including software engineer and sales support.

James Armstrong MEng (Hons)

James Armstrong is a Senior Engineering Consultant at LUSAS.

He spent 4 years as a structural engineer, working on the numerical design of high-rise buildings, before joining LUSAS in the support team. In his 8th year at the company he is now a senior member of the support team, assisting clients across a wide range of different modelling and analysis problems.

Nonlinear Analysis

Course summary

Who is it for?

In summary

What will I learn about?

Geometric nonlinearity (including large deflections)

Nonlinear materials

Nonlinear boundary conditions and contact analysis

Staged construction

Session details

Session 1 - Introduction to Nonlinear Analysis / Geometric nonlinearity

Session 2 - Material Nonlinearity

Session 3 - Nonlinear Boundary Conditions

Session 4 - Staged Construction

Accessing LUSAS

Options for downloading LUSAS

Web installer

Iso file

Instructors

Andy Taylor MEng CEng MICE

James Armstrong MEng (Hons)

Pages

Policy Pages

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