Stability Study of Arches Vaults and Domes Built by Compressed Stabilized Earth Blocks

Abstract

We base this paper on the building principles of Compressed stabilized earth bricks, a distinguished technique of earth construction. Objective of this research resides in maximizing the use of Earth as a construction material and replacement of steel, reinforced concrete cement as much as possible (less than 6-7% in most cases). The institute's continuous avant-garde attempts are opening new doors in Sustainable construction – eco-friendly and energy saving technologies.

The structural principles corresponding to the use of Earth as major construction material differ vastly from the everyday construction techniques using RCC etc which have been mastered to their capacities in many a aspects  by the Earth Institute. We will discuss our learning and research under Ar. Satprem Maini's guidance in relation to the construction techniques and principles of Arches, Vaults and Domes using compressed stabilized earth blocks.

The attraction of humans to Dome roofs, arches and vaults goes back to the beginning of settlement. Starting from simple conical huts and circular domes, man has come to build over 40-50 basic types of arches, vaults and domes.

The main principles of stability of this type of construction are based on the horizontal thrust forces, Weight loads and line of thrust in case of arches and an addition of hoop forces in case of domes. We discuss 2 methods to study any arch's stability: Catenary Method and the Funicular method. Architects have been using the catenary form for a stability test for years. The most prominent example would be of Antoni Gaudi's use of chains and links and gravity (makings of a catenary) in his designs.

The funicular method has been modified for this specific Earth Construction technique of the Institute. The Funicular study of an Arch (section) shows its exact stability profile and can easily specify the counter solution for future structural problems against common loads. It is the essential step for the Optimization method developed for unstable arch profile made for such construction. Optimization method has been especially developed for constructions without centrelines of arches, vaults as well as domes, despite their structural differences. The lightest arch's optimal section is taken and half of the arch is considered, with the thickness increasing from the top towards the bottom. Once an optimized profile is achieved, masonry pattern is defined, specific to the kind of earth blocks that are being produced in the laboratory.

We draw from personal practice and the study of real time projects structured on this method which is being used successfully in many parts of the world and is one of the most cost effective, Eco-friendly and energy saving methods of construction