# A Detailed Numerical Model for a New Composite Slim-Floor Slab System

## TL;DR

This paper introduces a detailed numerical model for a new composite slim-floor system that uses steel-concrete hybrid beams to improve construction efficiency and reduce material use.

## Contribution

The novelty lies in the development of a calibrated 3D finite element model for hybrid beams with advanced interface characterization and validation against experiments.

## Key findings

- A detailed 3D finite element model of hybrid beams was developed with accurate geometry and material representation.
- The model was validated through experimental field tests and analytical calculations, showing good agreement.
- The model can aid in planning experimental campaigns and calibrating design formulas for new construction systems.

## Abstract

The paper concerns the numerical modelling of a new slim-floor system with innovative steel–concrete composite beams called “hybrid beams”. Hybrid beams consist of a high-strength TT inverted cross-section steel profile and a concrete core made of high-performance concrete and are jointed with prestressed hollow core slabs by infill concrete and tie reinforcement. Such systems are gaining popularity since they allow the integration of the main structural members within the ceiling depth, shorten the execution time, and reduce the use of concrete and steel. A three-dimensional finite element model is proposed with all parts of the system taken into account and detailed geometry reproduction. Advanced constitutive models are adopted for steel and concrete. Special attention is paid to the proper characterisation of interfaces. The new approach to calibration of damaged elastic traction–separation constitutive model for cohesive elements is applied to concrete-to-concrete contact zones. The model is validated with outcomes of experimental field tests and analytical calculations. A satisfactory agreement between different assessment methods is obtained. The model can be used in the development phase of a new construction system, for instance, to plan further experimental campaigns or to calibrate simplified design formulas.