Engineered fiber-reinforced shotcrete for the blast retrofit of unreinforced masonry walls

世界各地最近发生的事件表明，现有建筑和基础设施在爆炸引起的爆炸荷载下是脆弱的。传统上，在加拿大的建筑设计中没有考虑爆炸载荷，因此迫切需要开发具有成本效益的方法来改造脆弱的结构（政府办公室、大使馆等），以提高爆炸性能并确保安全。砖石墙在许多老建筑中用作非承重（填充）墙或结构承重墙。现代规范要求砌体墙的钢筋最少，但老建筑没有这样的要求。因此，在加拿大城市和城镇的许多现有建筑中，无加固砌体墙（URM）对面外爆炸载荷的抵抗力非常低。此外，在低爆炸压力下发生故障可能导致形成高速飞行的碎片，从而伤害乘员。该项目将研究使用KING shotcrete Solutions开发的创新喷射混凝土（工程纤维增强喷射混凝土）的潜力，以提高现有URM墙的防爆性能。这种高性能、纤维增强、预包装和可喷喷混凝土已被开发用于地下隧道的保护衬里，以防止地震引起的高强度岩爆。由于提供短纤维，工程喷射混凝土具有非常高的韧性和能量吸收能力，使其成为极端爆炸载荷应用的理想选择。保护设计将涉及应用薄层工程纤维增强喷射混凝土作为一种快速和经济有效的URMwalls爆破改造方法。作为该项目的一部分，将使用渥太华大学的激波管对爆炸载荷下的全尺寸改造墙进行物理测试，该激波管能够安全准确地模拟爆炸产生的冲击波。该项目将产生一种创新的改造方法，为这种喷射混凝土产品开辟新的市场机会，并提高加拿大建筑物的爆炸安全性。

Recent events around the world have demonstrated the vulnerability of existing buildings and infrastructure toblast loads caused by explosions. Blast loads have traditionally not been considered in the design of buildingsin Canada, and there exists an important need to develop cost-effective methods to retrofit vulnerable structures(Government offices, Embassies, etc.) to improve blast performance and ensure safety.Masonry walls are used in many older buildings as either non-load bearing (infill) walls, or as structuralload-bearing walls. Modern codes require minimum steel reinforcement for masonry walls, but older buildingshave no such requirement. As a result, unreinforced masonry walls (URM) in many existing buildingsthroughout Canadian cities and towns have very low resistance to out-of-plane blast loading. Moreover, failureunder low blast pressures can lead to the formation of flying debris travelling at high speeds that can injureoccupants.This project will examine the potential of using an innovative shotcrete (Engineered Fiber ReinforcedShotcrete) developed by KING Shotcrete Solutions to enhance the blast performance of existing URM walls.This high-performance, fiber-reinforced, pre-packaged and sprayable shotcrete has been developed for use as aprotective liner in underground tunnels to protect against high-intensity rockbursts caused by earthquakes. Dueto the provision of short fibers, the engineered shotcrete has very high toughness and energy-absorptioncapacity, making it ideal for extreme blast load applications. The protective design will involve application of athin layer of Engineered Fiber Reinforced Shotcrete as a rapid and cost-effective blast retrofit method for URMwalls. As part of the project, physical testing of full-scale retrofitted walls under blast loads will be conductedusing the University of Ottawa Shock-tube, which is capable of safely and accurately simulating theshockwaves generated by explosions. The project will result in an innovative retrofit method that will open upnew market opportunities for this shotcrete product, and increase the blast safety of buildings in Canada.