ANALYSIS OF STUDIES ON INCREASING THE EXPLOSION RESISTANCE OF CONNECTIONS IN WOODEN STRUCTURES

Abstract

 Mitigation of the effects of the explosion is in the spotlight due to the unstable 
geopolitical situation. Existing wooden structures are not designed to withstand an explosive load, 
and in areas of a possible attack, their sensitive elements require anti-explosive modernization. The 
search for rational constructive solutions for connections that can plastically deform and dissipate the 
energy of an explosion, while preserving the supporting frame from destruction, is an urgent problem. 
The number of studies on the characteristics of connections of wooden structures under explosive 
loading is very limited and requires a holistic and systematic approach. Dynamic tests of connections 
of wooden structures using the Shock Tube installation, which is capable of creating high strain rates 
similar to those observed during explosions in the far zone, are presented. A load transfer device 
(LTD) with two third-span load transfer beams was used to convert the reflected shock tube pressure 
into  two  concentrated  forces  applied  directly  to  the  specimens.  While  the  structural  member  is 
subjected to a uniformly distributed load in a real explosion, the use of LTD generates similar strain 
rates and general dynamic responses in the timber member and connections. The LTD consists of 
rigid steel panels covering the entire opening of the end frame. Thanks to the slotted hinges, the LTD 
can move up to 200 mm, which allows the transfer of pressure without changing the rigidity of the 
tested  specimens.  A  technique  for  the  development  of  energy-absorbing  connections  (EAC)  in 
assemblies of glued laminated timber and cross-laminated timber (CLT) for protection against the 
impact of a blast wave is considered. Explosive overloads were modeled with the introduction of the 
Shock Tube installation. Experimental test results have shown that, when properly designed, EACs 
allow assemblies to withstand more blast energy than conventional glulam and CLT connections. The 
behavior of an EAC wood bar element under explosive loading can be divided into three stages. The 
initial loading stage is the region where both the EAC and the wood element behave resiliently by the 
time the EAC yields. The second stage is characterized by a yield plateau where EAC exhibits almost 
perfect ductility and the load acting on the wood element is constant. The last stage consists of a 
compaction stage accompanied by an increase in stiffness and strength, which exceeds the strength 
of the wooden element. Awareness of the need to protect wooden structures from significant dynamic 
effects (explosion, tornado) is an insufficiently solved problem. The analysis of literary sources made 
it possible to identify the advantages and disadvantages of different types of connections of wooden 
rod structures under the action of significant dynamic loads. Their advantages and disadvantages are 
determined, as well as the ways for their further improvement and application.