Strength without Size Effect and Formula of Strength for Concrete and Natural Marble

Abstract

Throughout the several-hundred-year-long history of the concept of strength, inaccurate material strength as a result of the size effect and the inconsistency of strength theories have been two continuous and challenging issues, and have even been taken to be inherent attributes of material strength. Applying the structural stressing state theory and method, this study experimentally investigates the uniaxial load-bearing process of concrete specimens and reveals their stressing state mutation features at specific load levels. Exploration of this general feature resulted in the discovery of essential strength, which is basically without size effect. Then, biaxial and triaxial experiments with concrete specimens were conducted in order to obtain the results for various combinations of principal stresses on essential strength. Consequently, according to Yu’s unified strength theory, the formula for strength of concrete was determined by fitting the relation between the combined principal stresses and the essential strength, which was verified by experiments carried out using natural marble specimens. Essential strength could promote the accuracy of strength indices, and the formula for strength might replace the existing strength theories for brittle materials. The initial solution of these two classic issues could make a new contribution to Yu’s unified strength theory and its final goal, promoting related research on material strength and leading to a more rational use of material strength in practical engineering.

Essential Stressing State Features of Laterally Loaded Masonry Wall Panels Revealed from Experimental Displacements

“…This study cited the experimental displacement data of 17 LLM wall panels tested by Chong [32]. There were several reasons to select the experimental data: (a) It wanted further to reveal that the general working law or the essential working behavior features also existed in the past experimental displacement data, like those revealed by the strain data [29][30]; (b) It wanted to enrich and develop the structural stressing state theory and the relative methodologies based on the experimental displacement data; (c) It wanted to indicate that the general working features of structures should become the basic reference to structural designs or the basic principle of structural designs. Fig.…”

“…Structural stressing state was defined as the response representation of a structure at a load level and could be described through modeling the experimental or simulative data such as displacements, stresses, strains and strain energy values [28][29]. Structural stressing state theory conducts the research into the general laws of material strength and structural load-bearing behavior as well as their applications.…”

“…Zhou developed his structural stressing state theory to try to break the bottleneck mentioned above [28][29][30][31]. The theory thought that the working process of a structure under a load case surely presented a stressing state mutation according to the natural law from quantitative change to qualitative change of a system.…”

Essential Design Strength and Unified Strength Condition of ETFE Membrane Material

“…As a result, the different strength indexes of ETFE membrane materials were proposed for design codes [ 3 ]. In total, the strength and design of ETFE membrane material have been following the conventional methods, such as the investigations of strength into other engineering materials such as concrete and metal: The material strength was commonly defined referring to the ultimate/peak loads of uniaxial specimens, which had the inherent uncertainty closely related to the initial defects of the material and the shape/size of the specimen [ 4 ]. Additionally, the ultimate strength was empirically reduced as the strength index of the material.…”

“…The material strength was commonly defined referring to the ultimate/peak loads of uniaxial specimens, which had the inherent uncertainty closely related to the initial defects of the material and the shape/size of the specimen [ 4 ]. Additionally, the ultimate strength was empirically reduced as the strength index of the material.…”