The Japanese domestic forests have never been maintained enough, and it was a great fear that the multiple functions of the forest such as watershed conservation, the land conservation, and so on has been declined. The construction employing the cross laminates timber (CLT) panels was offered as a method of large scale building in domestic and foreign countries. However, the seismic design method of CLT panel construction has never completed. So, in order to consider the seismic design method, the shaking table tests and static lateral load tests were conducted to the modelized CLT panel construction.
Various kind of in-plane bending tests of cross laminated timber (CLT) with different shapes have been previously carried out. The results indicate that the bending strength of CLT loaded in plane reduces as the number of layer increases. To evaluate this lamination effect on in-plane bending strength of CLT, a computational model based on Monte Carlo method was developed. The estimated bending strength showed the same tendency.
The wood engineering community has dedicated a significant amount of effort over the last decades to establish a reliable predictive model for the load-carrying capacity of timber connections under wood failure mechanisms. Test results from various sources (Foschi and Longworth 1975; Johnsson 2003; Quenneville and Mohammad 2000; Stahl et al. 2004; Zarnani and Quenneville 2012a) demonstrate that for multi-fastener connections, failure of wood can be the dominant mode. In existing wood strength prediction models for parallel to grain failure in timber connections using dowel-type fasteners, different methods consider the minimum, maximum or the summation of the tensile and shear capacities of the failed wood block planes. This results in disagreements between the experimental values and the predictions. It is postulated that these methods are not appropriate since the stiffness in the wood blocks adjacent to the tensile and shear planes differs and this leads to uneven load distribution amongst the resisting planes (Johnsson 2004; Zarnani and Quenneville 2012a). The present study focuses on the nailed connections. A closed-form analytical method to determine the load-carrying capacity of wood under parallel-to-grain loading in small dowel-type connections in timber products is thus proposed. The proposed stiffness-based model has already been verified in brittle and mixed failure modes of timber rivet connections (Zarnani and Quenneville 2013b).
The national research project to investigate proper structural design method for CLT (Cross Laminated Timber) buildings has been advanced by the subsidy of the Ministry of Land, Infrastructure, Transport and Tourism of Japan since 2011. This paper provides the outline of shake table tests executed as a part of the project in February 2015. Two specimens, one (Specimen A) is five story and another (Specimen B) is three story, were tested. As the result, for both specimens damage was rather slight by the strong input wave according to the Building Standard Law of Japan. Finally, Specimen A survived three dimensional input wave of 100% of JMA Kobe (strong ground motion recorded during Kobe Earthquake in 1995), and Specimen B survived 140% of JMA Kobe.
The in-plane shear specimens of full scale CLT panels are tested. From the test results, about the failure behaviour, if there is finger joint near the shear plane, cracks are tended to progress along the joint was confirmed. About the maximum shear unit stress was about 3N/mm2 , and shear stiffness was about 600GPa calculated as the total cross section effective.
CLT is composed of longitudinal layers and cross layers. When the CLT is used as shear wall, it is important to understand the in-plane shear performance in order to control the structural performance of wall and joints and the collapse mechanism. Therefore, the in-plane shear specimens of full scale CLT panels are tested.
The national research project to investigate proper structural design method for CLT(Cross Laminated Timber) buildings has been advanced by the subside of the Ministry of Land, Infrastructure, Transport and Tourism of Japan since 2011. This paper provides the outline, research item and main result stream of the project. Full-scaled building tests and element tests for evaluating seismic performance are described in this paper mainly. Numerical studies have been also conducting as well.
Structural possibility of CLT (Cross Laminated Timber) buildings in Japan is supposed to be smaller than that in other countries because of high seismic risk. In this paper, dealing 2 kind of middle-rise CLT panel construction method as objectives, the required wall quantity from the structural design method ruled in the building standard low of Japan is examined based on the knowledge from the national research project carrying out by the subsidy of MLIT (Ministry of Land, Infrastructure, Transport and Tourism) of Japan since 2011, and on the Japanese government notifications on structural design of CLT buildings issued on Apr. 1, 2016. As result, the required wall quantity in construction methods using rectangular narrow panel is generally regarded as practicable. However, reduction of wall quantity is expected for prevalence of CLT buildings. On the other hand, in construction methods using large rectangular panels with opening(s), the required wall quantity is confirmed generally 1.6 times larger than the former indicating poor practicability
Study on Seismic Performance of Building Structure with Cross Laminated Timber: Part 12: Objective and Loading Procedure and Accuracy of Static Loading Test
Cross-laminated timber (CLT) is a relatively new heavy timber construction material (also referred to as massive timber) that originated in central Europe and quickly spread to building applications around the world over the past two decades. Using dimension lumber (typically in the range of 1× or 2× sizes) glue laminated with each lamination layer oriented at 90° to the adjacent layer, CLT panels can be manufactured into virtually any size (with one dimension limited by the width of the press), precut and pregrooved into desirable shapes, and then shipped to the construction site for quick installation. Panelized CLT buildings are robust in resisting gravity load (compared to light-frame wood buildings) because CLT walls are effectively like solid wood pieces in load bearing. The design of CLT for gravity is relatively straightforward for residential and light commercial applications where there are plenty of wall lines in the floor plan. However, the behavior of panelized CLT systems under lateral load is not well understood especially when there is high seismic demand. Compared to light-frame wood shear walls, it is relatively difficult for panelized CLT shear walls to achieve similar levels of lateral deflection without paying special attention to design details, i.e., connections. A design lacking ductility or energy dissipating mechanism will result in high acceleration amplifications and excessive global overturning demands for multistory buildings, and even more so for tall wood buildings. Although a number of studies have been conducted on CLT shear walls and building assemblies since the 1990s, the wood design community’s understanding of the seismic behavior of panelized CLT systems is still in the learning phase, hence the impetus for this article and the tall CLT building workshop, which will be introduced herein. For example, there has been a recent trend in engineering to improve resiliency, which seeks to design a building system such that it can be restored to normal functionality sooner after an earthquake than previously possible, i.e., it is a resilient system. While various resilient lateral system concepts have been explored for concrete and steel construction, this concept has not yet been realized for multistory CLT systems. This forum article presents a review of past research developments on CLT as a lateral force-resisting system, the current trend toward design and construction of tall buildings with CLT worldwide, and attempts to summarize the societal needs and challenges in developing resilient CLT construction in regions of high seismicity in the United States.
