Development of a Life Cycle Assessment Allocation Approach for Circular Economy in the Built Environment

Transitioning the built environment to a circular economy (CE) is vital to achieve sustainability goals but requires metrics. Life cycle assessment (LCA) can analyse the environmental performance of CE. However, conventional LCA methods assess individual products and single life cycles whereas circular assessment requires a systems perspective as buildings, components and materials potentially have multiple use and life cycles. How should benefits and burdens be allocated between life cycles? This study compares four different LCA allocation approaches: (a) the EN 15804/15978 cut-off approach, (b) the Circular Footprint Formula (CFF), (c) the 50:50 approach, and (d) the linearly degressive (LD) approach. The environmental impacts of four ‘circular building components’ is calculated: (1) a concrete column and (2) a timber column both designed for direct reuse, (3) a recyclable roof felt and (4) a window with a reusable frame. Notable differences in impact distributions between the allocation approaches were found, thus incentivising different CE principles. The LD approach was found to be promising for open and closed-loop systems within a closed loop supply chain (such as the ones assessed here). A CE LD approach was developed to enhance the LD approach’s applicability, to closer align it with the CE concept, and to create an incentive for CE in the industry.

Reliability Analysis of a Solid Timber Column Subjected to Axial and Lateral Loading

In this paper, a reliability analysis of a solid timber column of square cross section subjected to axial and lateral loading in accordance with the design requirements of Eurocode 5 is carried out. Compression and bending were the two failure criteria considered in the reliability investigation. The First Order Reliability method was employed to solve the limit state functions formed from the two failure criteria and was coded in MATLAB for quick estimation of the reliability indices. The results obtained showed that both the load and slenderness ratios have effects on the reliability of a solid timber column. The results of the sensitivity analysis carried out on the stochastic variables showed that the reliability indices decreased with increase in slenderness ratio for 3m, 4m and 5m length of column considering both the compression and bending failure modes and decreased with increase in load ratio for 3m, 4m and 5m length of column considering both the compression and bending failure modes. The reliability indices also decreased with increase in length of column mode and decreased with increase in ratio considering bending failure mode. The reliability indices were also found to decrease with increase in load ratio for varying values of axial and lateral loads at constant slenderness ratio and length of column considering compression and bending failure modes. The choice of adequate and suitable dimensions having a lower slenderness ratio will enhance the reliability of the column. Keywords- Reliability analysis, solid timber column, Eurocode 5, failure criteria, slenderness ratio

DEFORMATION PERFORMANCE IMPROVEMENT IN TIMBER COLUMN–GROUND SILL JOINT REINFORCED USING ARAMID FIBER SHEET

We report the progress of an experimental study conducted to understand the seismic performance of a timber column–ground sill joint reinforced using an aramid fiber sheet, and to improve the deformation property of the reinforced joint. An aramid fiber sheet is a new material that weaves high-performance aramid fibers in one or two directions. In previous research, certain problems were found: (a) even when applying a similar reinforcement, the sheet did not necessarily demonstrate the same failure mode, and (b) when the sheet was peeled off in stretches, the joint is destroyed through brittleness. In this study, based on the preceding research, we proposed a new sheet-pasting method for an improvement in the deformation property, and conducted a bending test under cyclic loading for some column-ground sill joint specimens to verify the seismic performance and failure behavior. It was found that, by splitting the sheet, the problems of the preceding research are avoidable.

ANALYSIS OF TIMBER COLUMN-GROUND SILL JOINTS REINFORCED WITH IMPROVED ARAMID FIBER SHEETS

High-performance aramid fiber sheets are a new class of composite materials made up of weaved polyamide fibers. In this study, the seismic performance and failure behavior of timber column-ground sill joints reinforced with aramid fiber sheets were investigated. In a past study, we conducted bending tests under cyclic loading for three column-ground sill specimens. After reinforcing the specimens with aramid fiber sheets, the joint strength improved but was dependent on the method of attaching the sheet. It was found that the compression zone of the aramid fiber-reinforced plastic layer broke at the joint boundary. In this paper, we proposed an improvement in the method of attaching the fiber sheet to the joint. On the compression zone at the boundary of the joint, resin was not pasted onto the aramid fiber, the fiber was not cured, and the plastic layer was not formed. Therefore, we could solve some problems and control the failure of column-ground sill joints.