Post-breakage performance of pre-cracked laminated glass plates

Significance 

Glass has been used for decades to enhance the aesthetical appearance of buildings. In particular, laminated glass consisting of multiple glass sheets and polymeric layers is preferred over monolithic glass due to its good brittle properties. Just like other structural materials, they must, however, meet the safety requirements regarding the strength and ductility before and after breakage. To this end, post-breakage behaviors of broken laminated glass have been intensively explored. For instance, numerical and analytical models have been used to investigate crack propagation and failure behavior of various glass elements. However, these methods are not suitable for predicting the post-breakage behaviors of cracked laminated glass due to their strong discontinuity and nonlinearity. Consequently, depending on the kind of structural applications, the induced impact loads result in different cracked patterns that significantly affect the post-breakage performance of the laminated glasses.

Recently, researchers at Shanghai Jiao Tong University: Chenjun Zhao (Ph.D. candidate), Dr. Xinger Wang (Postdoctoral fellow), Iftikhar Azim (Ph.D. candidate) and led by Professor Jian Yang examined the post-breakage behavior of cracked laminated glass plates. Their experiment was based on two support conditions: bolted and simple. A total of twenty-one specimens in groups of seven were tested under a constant loading speed of 45 mm.min-1. The work is currently published in the journal, Construction and Building Materials.

In brief, the research team started their experimental work by applying a weight-drop impact load to crack the glass plates of all the specimens to enable the creation of patterns. Next, the cracked glass plates were subject to continuous static load until collapse. Based on the applied loads and deflection at seven reference points on the specimen, the effects of the initial stiffness and post-breakage resistance on the post-breakage performance were investigated. Finally, the key parameters in both the pre- and post-breakage phases were compared to determine the post-breakage capacity ratio.

Results confirmed that the support conditions influence the yield line pattern and the post-breakage performance. The initial stiffness of the cracked laminated plate with simple support was approximately four times higher than that with bolted support. Whereas various crack patterns resulted in different crack offsets, these offsets depended on the fragment size and glass type. On the other hand, annealed glass sheets yield the highest initial stiffness and resistance in the post-breakage phase as compared to the fully tempered glass. This was attributed to its favorable crack pattern and tension stiffness effect that facilitate the resistance performance. Additionally, the ability of the laminated glass to penetrate before the complete formation of the yield lines was enhanced by increasing the number of the SentryGlas interlayers.

In summary, Shanghai Jiao Tong University scientists conducted thorough experimental studies to investigate the static characteristics of laminated plates cracked by impacts. Hybrid configurations reported a slight increase in the initial stiffness and peak resistance by allowing for more delamination at the plate edges without losing much load earing capacity. Considering that most of the stiffness is induced by the intact glass layer, post-breakage stiffness was observed to be negligible as compared to that for the pre-breakage phase. Altogether, their study provides essential information that will advance our knowledge on cracked laminated glass plates.

 post-breakage performance of pre-cracked laminated glass plates - Advances in Engineering Experimental investigation into the post-breakage performance of pre-cracked laminated glass plates - Advances in Engineering Experimental investigation into the post-breakage performance of pre-cracked laminated glass plates - Advances in Engineering Experimental investigation into the post-breakage performance of pre-cracked laminated glass plates - Advances in Engineering Experimental investigation into the post-breakage performance of pre-cracked laminated glass plates - Advances in Engineering Experimental investigation into the post-breakage performance of pre-cracked laminated glass plates - Advances in Engineering Experimental investigation into the post-breakage performance of pre-cracked laminated glass plates - Advances in Engineering Experimental investigation into the post-breakage performance of pre-cracked laminated glass plates - Advances in Engineering

About the author

Chenjun Zhao is currently a Ph.D. candidate at School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University. His research interest lies on the structural performance of novel structural glass components and hybrid connections for glass structure.

Email: [email protected]

About the author

Professor Jian Yang is currently a professor in Civil Engineering, Shanghai Jiao Tong University. He obtained his PhD degree in University of Leeds, UK. He is an active and innovative researcher and practitioner. He serves as Fellow of ICE (FICE), Charted Engineering, Charted Member of IStructE, General Director of ICE Shanghai Branch. In his nearly 20 year’s research career, he has developed a wide spectrum of research interests.

Recent work encompasses the structural applications of sustainable construction materials/systems that cover recycled concrete, light gauge steel, structural insulated panels, glass and composites and the structural issues arisen from the off-site construction methods. In the last two years, he also embarked on a new research interest in smart construction and maintenance.

Email: [email protected]

About the author

Dr. Xing-er Wang is an active postdoc researcher in Department of Civil Engineering, Shanghai Jiao Tong University. His research interests focus on the topic related to glass materials and structures.

He acts as the key researcher in several national and Shanghai key research programs of glass and won two grants in the first year of work career in same area. Recent works encompass the impact damage prediction, structural use and durability, post-fracture performance of laminated glass. He is also trying to introduce artificial intelligence algorithm into the health monitoring system and surface scratches detection of glass façade.

Email: [email protected]

About the author

Iftikhar Azim is currently a PhD student in Shanghai Jiao Tong University. His research interests mainly involve progressive collapse of RC and precast structures and the applications of evolutionary algorithms for prediction purposes.

[email protected]

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Reference

Zhao, C., Yang, J., Wang, X., & Azim, I. (2019). Experimental investigation into the post-breakage performance of pre-cracked laminated glass plates. Construction and Building Materials, 224, 996-1006.

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