GROUT-FILLED BUCKLING RESTRAINED BRACES: INTERNAL CORE BEHAVIOUR AND FEASIBILITY OF ALTERNATIVE PVC CASING

Abstract

Buckling Restrained Braces (BRBs) are an innovative and popular seismic retrofitting solution with broad research on the behaviour of BRB-equipped structures. BRBs have been successfully used in buildings to resist earthquake actions. The device casing is traditionally made of steel, however, it is unclear whether other materials are a feasible alternative. Lighter and more economical casings may potentially benefit developing communities in earthquake-prone areas, moreover, durable and aesthetically preferred materials could also result in the fulfilment of architectural project requirements. Therefore, this thesis explores the possibility to use PVC/uPVC casing as an alternative to conventional steel casing through conducting both numerical and experimental studies. Dedicated 3D numerical BRB models are developed for this study. The specimen from published literature is first modelled to validate the finite element model through comparing the numerical and experimental results. A series of numerical investigations are conducted to simulate cyclical loading actions on BRBs and reveals the behaviour of the core yielding portion and quantify the lateral thrust exerted on the grout. The simulation provides an insight into the deformation and stress of cores subjected to cyclic loading. It is observed from the 3D modelling that the cores with a rectangular cross-section deforms independently in the two perpendicular directions when subjected to cyclic loading. This provides a basis to propose a 2D model to simulate the behaviour of BRBs, i.e. a full 3D model can be replaced by using two 2D models in the two perpendicular directions. The comparison between the results from the 3D and 2D models shows a good agreement. The use of the 2D model highly reduces the computational time of the modelling. Then numerical modelling and experimental studies of BRBs with PVC casing are conducted. The findings suggest that PVC can be a feasible and practical alternative to steel casings in situations where the inter-story drift is of reduced magnitude e.g. in low to medium-rise structures. In demonstrating the feasibility of a relatively low-cost material such as PVC, the work also paves the way for the investigation of other alternative casing products in the future.

Date of Award	1 Aug 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Tianjian Ji (Supervisor) & Lee Cunningham (Supervisor)