Design for Displacement Strains

The allowable stress for thermal expansion and other deformation-induced stresses is substantially higher than for sustained loads. This is due to the difference between load-controlled conditions, such as weight and pressure, and deformation-controlled conditions, such as thermal expansion or end displacements (e.g., due to thermal expansion of attached equipment).

Design and evaluation of exoskeleton for static conditions using Indian anthropometric considerations

Purpose Various occupations in life require personnel to stand for a prolonged period of time. This causes excessive stress on the joints leading to musculoskeletal disorders. This paper aims to design an equipment ensure the personnel rests on whenever necessary. Design/methodology/approach The method followed in this paper is the adoption of Karl Ulrich’s product design methodology with suitable modifications as per requirement. Human anthropometric data from the Indian population has been considered during the design and modelled according to it using computer aided design and computer aided engineering tools. Findings The conceptual equipment – exoskeleton designed sustained loads of human beings and proved to be a safe design in terms of the strength of the material used in the design. Social implications This design can serve as equipment, which helps the personnel with long-standing work hours to relieve themselves without actually sitting. Originality/value The design has been carefully crafted based on the inputs from the anthropometric features of human beings, which is completely passive in nature i.e. no use of external power is required for this exoskeleton compared to the other available designs.

Development of strength and elastic modulus of concrete sealed in steel tube under sustained load at early age

Concrete-Filled Steel Tubular Structures (CFSTSs) have become popular among the structural engineering community due to significantly higher load carrying capacity compared to conventional reinforced-concrete structures. Much research has been conducted on understanding the behavior of CFSTSs under various loading conditions and design theories have been established to predict the load carrying capacities of such structures. However, existing models do not consider the effects of sustained early loads on concrete strength and elastic modulus development of CFSTSs. With the need for rapid construction, CFSTSs may be subjected to loading at an early stage before concrete is fully cured. Such early loading may incur negative effects on strength and elastic modulus development of concrete within the confined environment. This paper propose theoretical models based on the compressive packing model (CPM) to simulate strength and elastic modulus development of early-age concrete under sustained stress. Development of concrete properties at early age is described using Hydration kinetics, and maximum paste thickness in the CPM model is modified using energy conservation to simulate sustained loads. Early concrete strength and the elastic modulus development rules were investigated experimentally for sustained loads. Predictions from the proposed models are compared with conventional models from CEB-FIP Model Code. Results showed that when loaded at a very early stage, a relatively high stress to strength ratio will result in causing damage in concrete. Such damage significantly affects the strength and elastic modulus development. Compared with concrete loaded at 28 days, concrete loaded at early stages showed significant reduction in concrete strength and elastic modulus.