Browsing by Author "De Silva, GTR"

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item: Conference-Abstract
Alternative foundation system for piles with soft toe condition
Chinthoory, G; De Silva, GTR; De Silva, A
This paper presents an alternative foundation system implemented for a 17 storied mixed development building at Kollupitiya. Initially, the foundation system of above building was designed to contain bored cast insitu piles driven to hard basement rock. During pile dynamic testing, the tested piles were found to undergo excessive settlements and failed to mobilize the expected design capacity due to soft toe condition. As an alternative for this problem, piled raft system was proposed and its feasibility was examined. Finite element modelling and analysis was carried out using SAFE v12 representing the raft as shell element and piles as springs. The simulation design and process is discussed in detail in this paper. The ‘conventional approach’ was highlighted in the design of raft with a load apportionment of 60:40 to piles and raft. While replacement of failed piles and rectification of piles incur significant time, cost and resources, the proposed piled raft system was found to be a sustainable and economical solution with least disturbance to the ground.
item: Conference-Abstract
Resource optimization with the use of precast slab system
(2019) Janaka, KG; Jayasinghe, C; De Silva, GTR
Resource optimization is one of the key themes in sustainable development. With fast growing construction industry over past few decades, consumption of natural resources has been on the rise. Rapid urbanization in Sri Lanka demands more and more multi-storeyed buildings, resulting a large quantity of resource utilization. The slab system which consumes lots of material and time is a key element of multi storied structures. The slab system also creates the highest amount of construction waste to the environment. Therefore, the research covered in this paper has been focused on a novel slab system developed with optimized resource utilization. The proposed slab system comprised of a pre-cast plank system designed as a hollow slab consisting of 60 mm thick precast concrete panel, light weight filler material using compressed straw boards and an in-situ screed concrete layer on top. The precast panels of 5.1 m span and 1.2 m wide consist of two trusses and BRC mesh. The proposed slab system optimizes the material consumption in the form of false work, formwork. The reusable steel mold used as formwork eliminate the use of timber and plywood. Erecting and assembling the proposed pre-cast system will consume much less time compared to that of in-situ construction. Steel shutters will create better surface finish so that the system needs less labour and material for the application of finishing coats. Pre-stressing of the slab can further optimize the system with reducing reinforcement requirement. The proposed slab system can promote cost effective construction with optimized use of materials and labour resulting faster construction and higher quality of the end product compared to the conventional slab system. Reuse of waste products such as paddy straw as a filler material and also reusing steel molds will further enhance the life cycle cost in the form of environmental benefits.