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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Multi-Panel CLT Shearwalls: Experimental Assessment, Analytical Development, and Design Considerations

Masroor, Mohammad 12 May 2023 (has links)
Analysis and design of Cross-Laminated Timber (CLT) walls under gravity loads have been outlined in the Canadian timber design standard with an adequate amount of details. The methods for designing shearwalls to resist lateral loads have not yet been fully developed, with only concepts being adopted, based on generalized capacity-based design concepts and definitions of yielding and non-yielding components. Several studies have focused on developing analytical expressions and design approaches for multi-panel CLT shearwalls, assuming angle brackets only behave in shear to prevent sliding, while ignoring compression zone effects in CLT panels. These assumptions may simplify the analysis, but they are not practical, especially since contemporary angle brackets are available on the market with uplift capacities comparable to those of hold-down connections. This study aimed to investigate the lateral behaviour of multi-panel CLT shearwalls and provided practical and comprehensive analytical expressions and design procedures for this type of structure. The analysis aimed to integrate the effects of all boundary connections, including hold-downs, angle brackets, panel-to-panel connections, and compression zones, into the analysis. On the basis of the developed analytical expressions, a capacity-based design procedure was proposed, which promoted rocking behaviour and optimized energy dissipation in the shearwall system. A novel yield hierarchy among various connections was introduced, and expressions for associated over-strength factors are proposed. For multi-storey applications, an approach which ensures uniform energy dissipation along the structure height and limits soft-storey failures was also presented. Experimental tests were conducted at the connection level to study the performance of conventional connections used in CLT shearwalls and to obtain their associated mechanical properties. Furthermore, the performance of multi-panel CLT shearwalls was investigated by conducting wall-level experimental tests to investigate the kinematic modes and establish levels of resistance and deflection. Numerical models were developed to verify the mathematical accuracy of the proposed analytical and design expressions. Also, to validate the proposed analytical expressions, they were compared against the numerical models, as well as the wall-level experimental tests. The results showed a reasonable match between the different approaches in terms of the general shape of the curves and kinematic behaviour.
2

Analytical Methodology to Predict the Behaviour of Multi-Panel CLT Shearwalls Subjected to Lateral Loads

Nolet, Vincent January 2017 (has links)
The increasing demand for more sustainable construction has led to the development of new structural systems that include wood as building material. Cross laminated timber (CLT) has been identified as a potential system to address this need and to provide alternative options in the range of low- to medium-rise construction. The appeal in using CLT as a shearwall is driven by the combination of the rigid panels and small dimension fasteners, which allows for significant energy dissipation in the structure. However, there is currently no reliable analytical model to accurately predict the behaviour of multi-segment CLT shearwalls. The current study aims to develop an analytical model capable of predicting the elastic and plastic phases associated with the behaviour of multi-panel CLT shearwalls. The model describes the wall behaviour as a function of the connectors’ properties in terms of stiffness, strength and ductility. This dependency means that the only input required in the model is the behavioural parameters of the connections. The proposed model contains six cases with a total of 36 different failure mechanisms. Two final wall behaviours were developed, and it was found that behaviour (i.e. single wall) could be achieved if the yielding in the hold-down occurred prior to yielding in the panel joints. Inversely, the other behaviour (i.e. coupled panels) was achieved if the yielding in the vertical joint occur prior to yielding in the hold-down. The analytical model was validated using a numerical model, and the results of the comparison showed very close match between the two models. The study proposed simplified design provisions with the aim to optimize the walls ductility (CP behaviour) or strength and stiffness (SW behaviour).
3

Seismic damage avoidance design of warehouse buildings constructed using precast hollow core panels

Abdul Hamid, Nor Hayati January 2006 (has links)
Precast prestressed hollow core units are commonly used in the construction of the flooring system in precast buildings. These units without transverse reinforcement bars are designed to resist seismic loading as replacement for fixed-base precast wall panels in the construction of warehouse buildings. Thus, this research seeks to investigate the seismic performance of the units constructed as a subassemblage (single wall) subjected to biaxial loading and as a superassemblage (multi-panel) subjected to quasi-static lateral loading. A design procedure for warehouse building using precast hollow core walls under Damage Avoidance Design (DAD) is proposed. In addition, a risk assessment under Performance-Based Earthquake Engineering (PBEE) is evaluated using the latest computational tool known as Incremental Dynamic Analysis (IDA). A comparative risk assessment between precast hollow core walls and fixed-base monolithic precast wall panels is also performed. Experimental results demonstrate that rocking precast hollow core walls with steelarmouring do not suffer any non-structural damage up to 2.0% drift and minor structural damage at 4.0% drift. Results revealed that the wall with unbonded fuse-bars and 50% initial prestressing of unbonded tendons performed the best compared with other types of energy dissipators. Furthermore, 12mm diameter of fuse-bar is recommended as there is no uplifting of the foundation beam during ground shaking. Hence, this type of energy dissipator is used for the construction of seismic wall panels in warehouse buildings. One of the significant findings is that the capacity reduction factor (Ø ) which relates to global uncertainty of seismic performance is approximately equal to 0.6. This value can be used to estimate the 90th percentile of the structures without performing IDA. Therefore, the structural engineers are only required to compute Rapid-IDA curve along with the proposed design procedure.

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