C8954 - PROGETTO DI STRUTTURE IN ACCIAIO E LEGNO M

Learning outcomes

At the end of the course, and after passing the final exam, students have advanced knowledge of: STEEL - introduction to recurring structural scheme of long-span structures, calculation and verification of complex structural elements including exceptional loads (e.g., fire, impacts, explosions), advanced method for buckling analyses. TIMBER - mechanical behaviour, recurring structural scheme in ordinary and large span structures, criteria for the design, calculation, and verification of solid wood, laminated timber, and CLT structural elements in static, seismic and exceptional conditions (e.g., fire, impacts, explosions). Students will have a good understanding of construction details and the main construction site operating methodologies. They will also be able to consult and interpret the main technical standards for structural design, with particular reference to the use of steel and wood.

Course contents

The course is organised around a number of cross-cutting themes in structural engineering, continuously comparing the behaviour of steel and timber structures. 1. Structural conception and design principles

• Evolution of steel and timber structures.
• Material selection according to structural typology and performance requirements.
• Design philosophy.
• Regulatory framework: Italian Building Code (NTC 2018), Eurocode 3 and Eurocode 5.

2. Timber as a structural material Introduction to timber products and their mechanical characteristics as the basis for structural design.

• Timber anatomy and structure.
• Orthotropic mechanical behaviour.
• Strength classes.
• Solid timber, glued laminated timber (GLT), laminated veneer lumber (LVL) and cross-laminated timber (CLT).
• Service classes.
• Moisture effects and load duration.
• Creep behaviour.
• Design principles for members subjected to tension, compression and bending, including loading parallel and perpendicular to the grain.

3. Connections in steel and timber structures Connections as a key component of structural behaviour.

Steel structures

• Bolted and welded connections.
• Design principles according to Eurocode 3.
• Rigid, semi-rigid and pinned joints.

Timber structures

• Dowel-type fasteners, bolts, screws and steel plate connections.
• Johansen's yield theory.
• Connection stiffness and deformability.
• Simplified modelling of connections in structural analysis.
• Design principles for steel-to-timber connections.

Role of connections in the global structural response. 4. Structural stability Structural stability as one of the governing design criteria for slender structures.

Steel structures

• Design of members subjected to tension, compression, bending and combined loading.
• Flexural and flexural-torsional buckling.
• Lateral-torsional buckling of beams.
• General Method of Eurocode 3.
• Finite element modelling of instability phenomena: linear buckling analysis, interpretation of buckling modes, introduction to geometric imperfections and limitations of linear analyses.

Timber structures

• Stability of compression members.
• Lateral stability of beams.
• Influence of connection deformability.
• Design criteria according to Eurocode 5.

5. Durability of structures Durability as a structural performance requirement.

Steel structures

• Corrosion mechanisms.
• Corrosivity categories.
• Protective systems.
• Design detailing for durability.
• Inspection and maintenance.

Timber structures

• Biological degradation.
• Moisture effects.
• Service classes and use classes.
• Design detailing for durability.
• Protection, inspection and maintenance.

Comparison of durability-oriented design strategies for steel and timber.

6. Structural fire design Fundamentals of structural fire engineering.

• Thermal actions and standard fire curves.
• Degradation of material mechanical properties under fire exposure.

Steel structures

• Mechanical behaviour at elevated temperatures.
• Critical temperature.
• Fire design according to Eurocode 3.
• Passive fire protection systems.

Timber structures

• Charring process.
• Effective cross-section method.
• Fire design according to Eurocode 5.
• Fire protection of connections.

Comparison of the fire performance of steel and timber structures.

7. Structural robustness

• Structural robustness and disproportionate collapse.
• Design principles for robustness.
• Structural redundancy.
• Alternative load paths.
• Role of connections.
• Robustness-oriented design strategies.
• Applications to steel, timber and hybrid structures.

8. Integrated design assignment: hybrid steel–timber structure Application of the course topics through the development of an applied design assignment including:

• structural conception;
• preliminary sizing and verification of structural members;
• finite element modelling;
• design of a representative connection;
• assessment of structural stability;
• fire design;
• durability-oriented detailing;
• robustness assessment of the structural system.

Readings/Bibliography

Recommended textbooks Steel structures

• G. Ballio, F. M. Mazzolani, C. Bernuzzi, R. Landolfo. Strutture di acciaio. Ed. Hoepli 2021

Timber structures

• Piazza M., Tomasi R., Modena R., Strutture in legno, Hoepli, 2005

Further reading Steel structures

• Nigro E., Pustorino S., Cefarelli G., Princi P., PROGETTAZIONE DI STRUTTURE IN ACCIAIO E COMPOSTE, Hoepli, 2009

Timber structures

• Laner F., Barbisan U., I solai in legno, Franco Angeli Editore, 1995
• Bardella L., Ceccotti A., Uzielli L., Manuale del legno strutturale, Mancosu Editore, 2003

Design standards

• Italian Building Code Norme Tecniche per le Costruzioni (NTC 2018) and related Commentary.
• EN 1993 – Eurocode 3: Design of Steel Structures.
• EN 1995 – Eurocode 5: Design of Timber Structures.
• Relevant National Annexes.

Teaching methods

The course combines lectures, discussion of case studies and applied learning activities through a problem-based learning approach. Lectures are complemented by the analysis of real structural applications, highlighting the rationale behind material selection, structural layout and construction detailing. Throughout the semester, students work in small groups on an applied design assignment concerning a hybrid steel–timber structure. The assignment is organised into progressive reviews aligned with the main topics of the course (stability, connections, durability, fire design and robustness), promoting the continuous integration of theoretical knowledge and engineering practice. Finite element modelling is introduced as a design support tool. The objective is not to train students in the use of a specific software package, but rather to develop their ability to critically interpret numerical results and use them appropriately within the structural design process. The course also includes design review sessions, during which students present and discuss their solutions.

Assessment methods

Assessment consists of two complementary components. The first component is the development, in groups of two or three students, of an applied design assignment concerning a hybrid steel–timber structure. The assignment includes structural conception, numerical modelling, preliminary design of the main members, design of a representative connection, and discussion of the main aspects related to structural stability, durability, fire design and robustness. Students submit a technical report together with the essential structural drawings. The second component consists of an oral examination, aimed at assessing the students' understanding of the theoretical topics covered during the course, their ability to critically interpret structural analyses, and their capability to justify the engineering choices adopted in the applied design assignment. The final grade is based on both the quality of the applied design assignment and the oral examination. 

Teaching tools

Whiteboard, projector, digital slides. Materials can be downloaded via distribution lists. Credentials will be provided by the instructor during the first lessons of the course.

Office hours

See the website of Luca Pozza