scholarly journals Cross-Laminated Timber Shear Walls in Balloon Construction: Seismic Performance of Steel Connections

Author(s):  
Hossein Daneshvar ◽  
Jan Niederwestberg ◽  
Carla Dickof ◽  
Jean-Philippe Letarte ◽  
Ying Hei Chui

In the context of the global trend of designing sustainable structures, the attention towards high-rise timber buildings of 8 to 25 storeys has been increasing in recent years. Balloon construction technique using a relatively new heavy timber material, cross-laminated timber (CLT), has been shown to be promising for high-rise building applications, given its compatibility with off-site construction techniques and its desirable mechanical characteristics. To date, tall timber buildings using CLT have been built mainly in non-seismic or low-seismic locations around the world, whereas their application in high seismic regions has been limited to platform construction. More research on the behaviour of CLT structures during seismic events in terms of system behaviour as well as the behaviour of components, particularly connections, is required. The research presented in this paper seeks to initiate the process of seismic design of tall wood buildings using a balloon construction technique. Two buildings, one three-storey fictitious building and one to-be-constructed ten-storey building, both located on the west coast of Canada, were considered and designed based on the NBCC 2015 seismic provisions. The loads on the shear walls, which span over three storeys, were extracted in order to estimate realistic demands on lateral load resisting systems (LLRS) in the balloon construction. Different connections, including base shear connections, panel-to-panel shear connections, as well as high-capacity hold-downs, were designed accordingly. An experimental program was developed to investigate the behaviour of these connections, focusing on yielding and failure mechanisms in each connection category. This paper explains different phases of the experimental program and introduces connection details designed to achieve the research goals. The results of this study will contribute to the body of knowledge on seismic behaviour of prefabricated mass timber buildings, and will benefit engineers and practitioners using timber to design high-rise structures.

In the modern era, the growth of population has influenced the construction of high rise buildings day by day. The construction of the building structures with conventional RC slabs are in the public eye since many decades. Although it has more stiffness and minimizes the large moments occurred due to the applied loads, it does not have the advantages in terms of architectural flexibility, easier formwork and shorter construction period compared to the flat slabs. This developing technique of flat slabs construction improves aesthetical and structural aspect of tall building, offices, hospitals, shopping malls etc. As this is considered to be beamless slab, it has less shear strength and less stiffness compared to the conventional slabs. Due to its huge advantages, it is common in both the construction of regular and irregular buildings nowadays. From Structural engineer’s point of view, the flat slabs should be adopted with other structural component like shear walls and bracings for better results. The main motive of the present work is to compare and observe the seismic behaviour of regular and different configuration of irregular building in zone V by using different types of flat slabs. The considered G+13 storied buildings were analyzed with flat plate, drop panel, column head and combination of column head & drop panel by using E-tabs 17.0.1 software. The nonlinear time history method was carried out to observe the different parameters like storey displacement, storey drift, storey shear, base shear and time period following the guidelines of IS 1893 (Part 1): 2016


Buildings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 162 ◽  
Author(s):  
Cristiano Loss ◽  
Stefano Pacchioli ◽  
Andrea Polastri ◽  
Daniele Casagrande ◽  
Luca Pozza ◽  
...  

Changes to building codes that enable use of materials such as cross-laminated timber (CLT) in mid- and high-rise construction are facilitating sustainable urban development in various parts of the world. Keys to this are the transition to multi-performance-based design approaches along with fewer limitations on heights or the number of storeys in superstructures constructed from combustible materials. Architects and engineers have increased freedom to apply new design and construction concepts and methods, as well as to combine timber with other structural materials. They also have started to develop wall arrangements that optimise interior space layouts and take advantage of the unique characteristics of CLT. This paper discusses the seismic response of multi-story buildings braced with a CLT core and perimeter shear walls anchored to foundations and floor platforms using modern high-capacity angle brackets and hold-downs, or X-Rad connectors. Linear dynamic finite element (FE) models of seismic responses of superstructures of various heights are presented, based on experimentally determined characteristics of wall anchor connections. Particular attention is given to fundamental vibration periods, base shear and uplift forces on walls, as well as inter-story drift. Discussion of FE model results focuses on structural engineering implications and advantages of using CLT to create shear walls, with emphasis on how choice of wall anchoring connections impacts the possible number of storeys and configurations of superstructures. Employing CLT shear walls with X-Rad or other types of high capacity anchoring connections makes possible the creation of building superstructures having eight and potentially more storeys even in high seismicity regions. However, it is important to emphasise that proper selection of suitable arrangements of shear walls for CLT buildings depends on accurate representation of the semi-rigid behaviors of anchoring connections. The linear dynamic analyses presented here demonstrates the need during engineering seismic design practices to avoid use of FE or other design models which do not explicitly incorporate connection flexibilities while estimating parameters like fundamental periods, base shear and uplift forces, as well as inter-story drift.


Author(s):  
Jean Pierre Lukongo Ngenge ◽  
Abdallah M. S. Wafi

This paper gives a brief presentation about different types of analysis, plastic hinge, moment-resisting frames (MRFs) and shear walls (SWs) in reinforced concrete (RC) Structures. ETABS computer software is employed to model and analyse the structures applying the pushover. The performances of the modelled structures are also evaluated considering different parameters such as the number of stories, spans length, shear walls, reinforcement yield strength and characteristic strength of concrete. The study includes two cases, which are moment-resisting frames with and without shear walls (i.e. MRFs and MRF-SWs, respectively). Each case covers low-, mid- and high-rise buildings. In this regard, a comparative study has been performed for the results obtained from all models. It was observed that the stiffness of MRFs compared to MRF-SWs was less and also the stiffness of low-rise frames was higher than that of mid-rise and high-rise frames. Technically this means that a low-rise building is stiffer than a mid-rise building and a mid-rise building is stiffer than a high-rise building. Additionally, when the span length increases, the stiffness of the building decreases. Therefore, it can be concluded that the span length is inversely proportional to the stiffness. Finally, all stiffness values were calculated taking into consideration the displacement and base shear at the first hinge formation on the pushover curve of each model.


Author(s):  
Hridya. K

Torsion force is a load that is a applied to a building through torque. The torque applied creates a shear stress. If a torsion force is large enough, it can cause a building to undergo a twisting action. The main aim of the project is to study the effect of location of shear wall on torsional performance of symmetric and asymmetric high-rise building ,post tensioned slabs are being used in the construction of building hence the thesis also analyze these post tensioned slab structures by changing shear wall configuration. Post tensioned slab structures have weak resistance to lateral loads. so to provide stiffness to structures against lateral forces shear walls are used. A study of 30 storey building in zone III, is considered and determine various parameters like base shear, storey drift, and storey displacement.post-tensioning is a mature technology as it provide efficient, economic and elegant structural solutions for a wide range of applications. Post-tensioned flat slab could be a better option compared to RCC flat slab, in respect of the cost of project and time of construction. ETABS 2017 software is used for the analysis.


Author(s):  
Varun Mahajan

Abstract: Architects nowadays develop attractive edifices, and floating columns are widely employed in this process. Floating columns are used not only to provide a magnificent perspective but also when a vast open area is necessary. Edifices with irregular configurations are more vulnerable to earthquakes and hence, suitable shear wall placement is required to ensure the edifice's stability. Many multi-storey edifices collapsed in seconds after the Bhuj Earthquake (Jan 26, 2001), due to the presence of soft stories, floating columns, and mass anomalies. As a result, knowing the seismic reactions of these buildings are vital for constructing earthquake-resistant assemblies. The relevance of a Floating Column and the existence of a shear wall in an irregular multistorey building is highlighted in this study. Dynamic seismic behaviour of a G+18 irregular edifice with different locations of the floating column and different positions of the shear wall is explored in this research. The edifice is analysed and compared with the model without shear walls and floating columns to examine the alterations. The dynamic analysis is carried out using Response Spectrum Analysis and storey drift, storey displacement and base shear are calculated and finally, software compression is computed for different zones. The analysis is carried out by Indian standardized codes IS 1893:2016 and IS 456:2000 which are the codes specified by the Bureau of Indian Standards for earthquake resistance edifice design and plain and reinforcement concrete design respectively. Keywords: Floating Column, Shear Wall, Irregular Edifice, Seismic behaviour, Response Spectrum Analysis, storey drift, storey displacement, base shear.


2021 ◽  
Vol 10 (1) ◽  
pp. 1-11
Author(s):  
Sneha Benoy ◽  
Asha Joseph

Shear walls are specifically meant to withstand lateral forces exerted by either wind or earthquake loads on a structure. Due to their superior strength and stiffness, shear walls have been an integral feature of mid-rise and high- rise structures over the past two decades. Various studies have been performed in this field. Usage of post-tensioned tendons in the traditional shear wall is one of the major advancements in recent times so as to increase the stiffness and reduce the damage incurred by destructive earthquakes. The key advantage of post-tensioned shear walls is the potential to re-centre after a devastating earthquake which is lacking in conventional reinforced concrete (RC) shear walls that rely on yielding creating large deformations. Moreover, compared with conventional shear wall construction, post-tensioned shear walls can reduce the use of vertical mild steel reinforcement. This results in materials being used more effectively and eliminates congestion. This paper seeks to review and analyze the research studies based on post- tensioned shear wall focusing on works published within the last decade. Firstly, the benefits of using post-tensioned shear walls in seismically active areas are illustrated. The behaviour and parameters controlling the performance of post-tensioned shear walls are then studied. A critical study of the factors responsible for the performance of post- tensioned shear wall is the primary objective of this review. Keywords- Shear Wall, Post-Tensioning, Energy-Dissipation, Self-Centering


Due to gradual development of metros and small towns and increasing population in India, the high rise buildings are constructed at a larger scale due to land scarcity and the commercial or cultural importance of a particular area. A high rise building should be architecturally viable and should have good light and air ventilation. In this project we compare and analyze the high rise buildings in three configurations.A high rise building is a structure which is more than 30m in height. In this project we consider a high rise building with story configuration of G+20. The three configurations of the high rise building are designed, configured and seismically analysed using ETABS software. Earthquake analysis in ETABS is carried out on Model (a)-Structure without a shear wall, Model (b)-Structure with shear walls and Model (c)-Structure with openings in shear walls resting in Type II soil and Type III seismic zone. The soil type and seismic zone considered for this project is specific for Amaravati the capital of Andhra Pradesh. Seismic analysis results for each configuration of the high rise building such as Base Shear, Time Period, Storey Drifts and Displacements are compiled and compared to find the suitable configuration of high rise structure.


2020 ◽  
Author(s):  
◽  
Hosein Asgari

Cross-laminated Timber (CLT) is increasingly being used in tall buildings. However, there are some challenges when designing high-rise CLT structures, amongst them the need for novel hold-downs (HD), for shear walls. While commonly used HDs behave as a dissipative connection, the current Canadian Standard for Engineering Design in Wood recommends designing HDs as a non-dissipative connection. As hyperelastic material, an elastomer (rubber) is capable to carry high loads without inelastic deformation. This thesis presents experimental studies at material- and component-levels using a hyperelastic rubber HD solution for CLT walls. A total of 53 quasi-static monotonic and cyclic tests were performed. The HDs exhibited high strength and deformation capacity without any residual deformation after unloading. The shape factor and loaded area of rubber layers were found as the main effective factors on the rubber HD’s response, and an empirical load-displacement relation was also developed based on these parameters.


2021 ◽  
Vol 7 (2) ◽  
pp. 119-130
Author(s):  
M Mirza Abdillah Pratama ◽  
Septiana Dyah Sugmana Putri ◽  
Edi Santoso

Shear walls in high-rise buildings serve to increase the resistance of high-rise buildings to lateral loads. This study aims to compare the structural performance of an existing 8 (eight) storey building designed as a special moment resisting frame structure against a building designed as a dual system, which consists of: structural vibration time, base shear force, displacement, and drift. Three configurations for shear walls are designed, as follows: (1) L-shaped located at the corner of one side of the building, totaling 2 (two) units (SW1); (2) L-shaped located at the four corners of the building totaling 4 (four) units (SW2); and 3) I-shaped located along the side of the building totaling 6 (six) units (SW3). Simulations are run using the Etabs by taking into account dead loads, live loads, and earthquake loads. The results show that the addition of shear walls can: (1) reduce the vibration period of the structure up to 62,55% in SW3, (2) increase the base shear force up to 86,34% in SW3, (3) reduce peak displacement up to 84,86% in SW3, and (4) reduce the drift between floors up to 89,58% in SW3. However, the SW2 is considered to be better applied to the building by taking into account the structural performance, effectiveness and efficiency factors.


2021 ◽  
Author(s):  
◽  
Abubakar Oyawoye

Cross-laminated timber (CLT) continues to establish a stronger footing in the Canadian construction industry, also as an option for lateral load resisting systems, such as shear walls. Recent modifications to the Canadian Standard for Engineering Design in Wood (CSA O86- 19) allow only rocking kinematics as energy dissipative mechanics for CLT shear walls, whereby hold-down must remain elastic. These provisions necessitate the development of novel hold-down solutions. In this report, the performance of a hyper-elastic high-capacity hold-down was investigated at the component level through tests on: (1) hold-down steel rod, (2) CLT housing, and (3) hold-down assemblies with different sizes of rubber pads. The tests demonstrated that: i) the rubber hold-down can remain elastic under a rocking kinematics provided that the elastic limit of the steel rod is not exceeded; ii) failure of the rod is the subsequent desired ductile mode; iii) the CLT width influences the failure mode; iv) the shape factor influences the achievable deformation of the rubber pad; v) increasing the rubber pad thickness reduces the hold-down stiffness; and vi) increasing the rubber pad width increases the hold-down stiffness. Numerical modelling and optimization suggested that using an intermediate steel laminate between layers of rubber pads could improve its performance. Based on the results of the investigations presented herein, a capacity-design procedure for the hyper-elastic hold-downs was proposed.


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