Wood is increasingly perceived as a renewable, sustainable building material. The carbon it contains, biogenic carbon, comes from biological processes; it is characterized by a rapid turnover in the global carbon cycle. Increasing the use of harvested wood products (HWP) from sustainable forest management could provide highly needed mitigation efforts and carbon removals. However, the combined climate change benefits of sequestering biogenic carbon, storing it in harvested wood products and substituting more emission-intensive materials are hard to quantify. Although different methodological choices and assumptions can lead to opposite conclusions, there is no consensus on the assessment of biogenic carbon in life cycle assessment (LCA). Since LCA is increasingly relied upon for decision and policy making, incorrect biogenic carbon assessment could lead to inefficient or counterproductive strategies, as well as missed opportunities. This article presents a critical review of biogenic carbon impact assessment methods, it compares two main approaches to include time considerations in LCA, and suggests one that seems better suited to assess the impacts of biogenic carbon in buildings.

Abstract:Timber building has gained more and more attention worldwide due to it being a generic renewable material and having low environmental impact. It is widely accepted that the use of timber may be able to reduce the embodied energy of a building. However, the development of timber buildings in China is not as rapid as in some other countries. This may be because of the limitations of building regulations and technological development. Several new policies have been or are being implemented in China in order to encourage the use of timber in building construction and this could lead to a revolutionary change in the building industry in China. This paper is the first one to examine the feasibility of using Cross Laminated Timber (CLT) as an alternative solution to concrete by means of a cradle-to-grave life-cycle assessment in China. A seven-storey reference concrete building in Xi'an was selected as a case study in comparison with a redesigned CLT building. Two cities in China, in cold and severe cold regions (Xi'an and Harbin), were selected for this research. The assessment includes three different stages of the life span of a building: materialisation, operation, and end-of-life. The inventory data used in the materialisation stage was mostly local, in order to ensure that the assessment appropriately reflects the situation in China. Energy consumption in the operation stage was obtained from simulation by commercialised software IES TM , and different scenarios for recycling of timber material in the end-of-life are discussed in this paper. The results from this paper show that using CLT to replace conventional carbon intensive material would reduce energy consumption by more than 30% and reduce CO 2 emission by more than 40% in both cities. This paper supports, and has shown the potential of, CLT being used in cold regions with proper detailing to minimise environmental impact.

Shape-memory alloys are known to have two unique characteristics: a shape-memory effect and superelasticity. The shape-memory effect is the ability of the alloys to revert to their initial shape upon being heated until they enter their phase transformation temperature. Superelasticity is where the alloys exhibit comparatively large recoverable strain. Different families of shape-memory alloys have different suitable applications due to their different ranges of transformation temperature, as depicted in Figure 1 (Omori et al., 2011). For example, aluminium-manganese and iron-nickelcobalt-aluminium shape-memory alloys are suitable for seismic application as their working temperatures cover the range of-50°C to 50°C. Different families of shape-memory alloys have different advantages and disadvantages. Shape-memory alloys have been developed since the early 1960s. They have been successfully used for medical (

nect beam and column. In Japan, Nuki joints are usually used in traditional temples, and are commonly used in rural residential buildings. Much attention has been paid to the study of the structural behavior of these traditional timber joints in Japan. [4][5][6] One of the significant results was contributed by Inayamal; 7 who developed a model to predict the rotational stiffness of Nuki joints by considering the embedded force between column and beam. This model is frequently applied in Japan. The same timber joints can be found in Chuan-Dou timber frames in rural residential houses in Taiwan. However, unlike those in Japan, the Nuki joints in Taiwan are not fitted with wedges, which means that there is usually a gap between beam and column.A recent trend in analyzing timber structures involves considering the timber connections as semirigid joints. 8,9 However, little research has focused on traditional timber structures in Taiwan to date. The first research on timber joints in Taiwan was conducted by King et al., 10 in which one third scale specimens were used to study the rotational stiffness. Chang and Hsu 11 studied the hysteretic behavior of traditional timber joints in Taiwan. Because the rotational stiffness of timber joints needs to be known to properly analyze structures, there is an urgent need to study the mechanical behavior and propose a model for predicting the rotational stiffness of traditional timber joints. This study examined the rotational performance of traditional timber joints in Taiwan. Field investigationsBecause of a lack of background information on traditional timber connections in Taiwan, an extensive survey on a total of 84 historic buildings was carried out, in which 4 of these historic buildings were dismantled. The surveys on these 4 dismantled buildings helped us to clarify the types of timber connections that currently exist. The results of the field survey showed that timber joints used three different types of connection, designated as continuous connections, dovetail connections, and simple-contact connections, as illustrated in Fig. 1. The member-geometry results of the Abstract The Nuki joints in Taiwan and Japan are similar in appearance; however, due to lack of wedges used in Nuki joints in Taiwan, the gap between the column and beam increases the complexity of timber joints. In this article, the rotational performance of traditional timber joints is reported. A theoretical model considering Hook's law and Hankinson's formula was developed for predicting the rotational performance of Nuki joints with gaps. A total of 24 specimens was tested and used to verify the rotational performance of timber joints. The proposed model not only predicts the rotational stiffness of Nuki joints, but can also estimate the initial slip of these joints. Good agreement was found between predicted and experimental data.

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