A novel approach to in-depth façade assessments: Improved corrosion test methods for embedded steel framing in historic masonry clad buildings

Gina Crevello,Irene Matteini,Paul Noyce,M.G Grantham,C Mircea

doi:10.1051/matecconf/201928907002

Abstract

Corrosion of structural steel frames and associated steel assemblies within ‘vintage’ buildings circa 1880s to 1930s pose a health and safety risk to the public in major urban centers. The projecting masonry elements pose a particular concern when the underlying steel assemblies and anchorage begin to corrode. Failed masonry has fallen from buildings, leading to death in worst case scenarios. While some signs of masonry cracking or displacement are usually visible prior to failure, the level of degradation of the embedded steel is not. With the equipment available to test these unforeseen conditions, methodologies need to be shifted to understand unobservable conditions to assist in condition state ratings of embedded steel. In many cities, building owners are being faced with large expenditures to strip and replace terra cotta or stone elements where the underlying steel is in fair condition. This paper will discuss the field-testing programs where a building elevations' masonry clad, steel assemblies (outriggers, anchorage and cross bracing) were evaluated for corrosion. The testing program assessed various steel components which either projected from the structure or were embedded at great depth with a bespoke, in-depth advanced testing program geared towards the development of condition state ratings for the façade elements.

Highlights

Corrosion of embedded structural steel in masonry clad buildings can lead to extensive maintenance and repair costs to the owner, the loss of structural integrity of the corroding members, and can pose life safety issues to pedestrians should masonry fall from overhead
The following tables provide the analysis in accordance with the condition state rating for corrosion: Table 4
The following tables provide the analysis in accordance with the condition state rating for corrosion: Table 6. 3D Results Balconies and Balconettes

Summary

Introduction

Corrosion of embedded structural steel in masonry clad buildings can lead to extensive maintenance and repair costs to the owner, the loss of structural integrity of the corroding members, and can pose life safety issues to pedestrians should masonry fall from overhead. The results of corrosion related damages to masonry cladding are evident on the façade, the degree of internal degradation of the steel is unknown. Traditional methods of material analysis include visual inspections and sounding surveys to determine quantifiable damage to the cladding, non-destructive evaluations to understand cracking of the masonry, and water infiltration and laboratory testing to determine material performance properties of the masonry units. Corrosion testing programs allow the owners and design team an understanding of complex conditions within the building envelope which are often unseen during a traditional inspection. The resulting analysis provides a correlation of the unobserved conditions with steel section loss, which minimizes destructive investigations and can provide categorizations of future corrosion conditions. The knowledge gathered allows the team to make proactive repair choices on established corrosion condition states and helps budget funding based on anticipated degradation

Methods

Results

Conclusion