Dynamic Analysis of Large-Scale Wooden Structures with a Core of Reinforced Concrete and Considering Wooden Diaphragm Stiffness : Part1. Background and Analysis Models
The purpose of this paper is to outline the foundation for the research by presenting the underlying design philosophy and resulting design framework that will serve as the basis for the emerging design methodology. In this way, context will be provided for the technical papers to follow and the eventual design methodology at the project’s conclusion. A companion paper, “Seismic Design Methodology for Precast Concrete Diaphragms—Part 2: Research Program,” describes the specific analytical and experimental activities taking place in the research.
Dynamic Analysis of Large-Scale Wooden Structures with a Core of Reinforced Concrete and Considering Wooden Diaphragm Stiffness : Part2 Results of Response Analysis and Studies
The purpose of this paper is to outline the foundation for the research by presenting the underlying design philosophy and resulting design framework that will serve as the basis for the emerging design methodology. In this way, context will be provided for the technical papers to follow and the eventual design methodology at the project’s conclusion. A companion paper, “Seismic Design Methodology for Precast Concrete Diaphragms—Part 2: Research Program,” describes the specific analytical and experimental activities taking place in the research.
Although wood is widely used as a construction material, it is mostly limited to low and mid-rise residential construction, partially due to fire code restrictions. This limitation can be overcome by considering hybrid systems which combine wood with non-combustible materials. This research presents an innovative wood-concrete hybrid system, suitable for tall buildings, where a concrete frame with slabs at every third story provides fire separation as well as stiffness and strength to resist gravity and lateral loads. The intermediate stories including their floors are constructed using light-frame wood modules. This approach reduces the environmental footprint of the building, reduces the building weight and therefore the seismic demand on connections and foundation, and speeds up the construction process. For a novel system, numerical modeling is crucial to predicting its structural response to static and dynamic loading. This thesis studies the structural feasibility of the system by developing finite element models and assessing the structural behavior at the component and system levels when subjected to earthquake and wind loads. Nonlinear analyses are performed considering material and geometric nonlinearity using multiple ground motions to estimate the structure’s inter-story drift and base shear. The results demonstrate the feasibility of the proposed wood-concrete hybrid system for tall buildings in high seismic zones.
Seismic torsional responses in buildings is a result of eccentricity in mass and stiffness distribution. Torsional irregularity is one of the major causes of severe damage and collapse of structures during an earthquake. In this study, effect of torsion on the structures is reviewed, the definition of torsional irregularity and the characteristic of the structure that leads to this type of irregularity is elaborated. The evolution of the methods to consider the effect of torsion in the National Building Code of Canada (NBCC) is reviewed and different methods to prevent torsional irregularity in the structures are discussed. Hybridization with Cross-Laminated Timber (CLT) is suggested as a new method to rectify the effect of torsional irregularity for different performance levels. Accordingly, the definition of hybridization and hybrid structure seismic behavior, CLT material specifications and CLT seismic performance is discussed. In order to evaluate the effect of CLT hybridization on buildings with torsional irregularity, a four-storey reinforced concrete (RC) structure with torsional irregularity is considered for Vancouver seismicity condition. SAP2000 software is used to conduct Linear Dynamic Analysis (LDA) and Non-Linear Time History Analysis (NLTHA) using eight different ground motion scaled to Vancouver design spectra. The effect of the CLT wall panel as shear wall on the in plane seismic base shear and inter-storey drift is shown using the linear and non-linear dynamic analysis. The result from the analysis compared to the code static values. The literature of Performance Based Seismic Design (PBSD) is reviewed. PBSD is used to determine the performance level of the original and hybrid building. The inter-storey drifts criteria defined in FEMA 356 guidelines is used for the purpose of NLTHA.
The benefits of using wood in tall and commercial construction are undisputed, namely reducing the carbon footprint, shortening construction times, and enhancing seismic and building physics performance. The international market for wood as a structural material in tall and non-residential construction, however, is still relatively untapped. China is home to the world’s largest population and the largest construction sector worldwide, yet wood products are only used in a small fraction of buildings. The main reasons for this situation are the fire regulations and lack of guidelines for novel wood-based structural systems. This paper describes the design of a 10-storey timber-concrete business hotel which will be erected in the Guizhou province of China. The foundation design, gravity system design, lateral load resisting system design, seismic analysis and the fire resistance design were conducted, and the procedure provided appropriate information to the technological feasibility to promote the development of timber-based hybrid high-rise construction systems in China.
