Dissemination DeliverablesD5.3

Deliverable 5.3

Abstract

This deliverable, developed within the CIRCULAR WELD project, presents guidelines for the sustainability assessment of the Dot-by-Dot (DbD) Wire Arc Additive Manufacturing (WAAM) process and its structural applications. The document provides a structured framework to evaluate the environmental performance of DbD WAAM elements, with a specific focus on strut-based lattice structures.

Building upon the strut-based lattice topologies and unit cells introduced in Deliverable 4.2, where the fundamental unit was defined as the Diamond Cell (D-cell), the present deliverable further develops this framework by introducing Diamond WAAM elements. These elements are generated through the repetition of D-cells along a straight or curved path, forming structural components referred to as Diamond elements (D-elements). In the present study, a curved geometric configuration is considered with the aim of further optimizing the structural behavior of a novel curved damping device recently proposed for the seismic retrofitting of pinned steel frames. Among the two D-cell configurations introduced in Deliverable 4.2, namely the Diamond Frame and the Diamond Truss, the Diamond Truss configuration is adopted for the development of the final demonstrator of the project.

The final demonstrator consists of a lattice-based corner Crescent Shaped Brace (CSB), conceived as an innovative energy-dissipation device for beam-to-column joints. The demonstrator belongs to the category of D-elements and is realized through strut-based D-cells. It is designed as a replaceable hysteretic component providing lateral stiffness and energy dissipation. The design procedure of the curved energy-dissipative device is first illustrated with the aim of satisfying multiple seismic performance objectives.

The manufacturing process sustainability indicators used for the assessment in the DbD WAAM process is presented, with specific reference to the process parameters influence. Building upon the results previously obtained from the investigation of single rods and intersecting rods, the deposition strategy is applied to the fabrication of lattice structures, ensuring that D-elements are manufactured with controlled geometrical accuracy and printing quality. Particular attention is devoted to the process stages contributing to material and energy consumption, which form the basis for the environmental assessment.

A cradle-to-gate Life Cycle Assessment (LCA) approach is adopted to quantify the carbon emissions associated with the production of DbD WAAM elements. The methodology explicitly accounts for the different WAAM process stages and includes a comparative assessment with conventionally manufactured counterparts. The environmental assessment is applied to the lattice-based corner CSB and its environmental performance is compared with that of the previously conceived and designed full solid corner CSB, characterized by a boomerang-like geometry and a solid cross-section, in order to assess the environmental performance of the WAAM-enabled lightweight solution.

Table of contents

1.     INTRODUCTION

2.     SEISMIC DESIGN OF CURVED ENERGY-DISSIPATION DEVICES FOR THE SEISMIC RETROFITTING OF PINNED STEEL FRAMES

3.     MANUFACTURING PROCESS SUSTAINABILITY INDICATORS

4.     LIFE CYCLE ASSESSMENT APPROACH