The effect of constant and seasonal changes of ambient conditions on long‐term behavior of high‐rise concrete structures

Abstract

Summary Temperature is one of the most important factors affecting the long‐term behavior of concrete: Its remarkable impact is directly involved in the analysis and design of structures. In this paper, the effect of ambient temperature on the development of modulus of elasticity, creep, and the shrinkage of concrete with time is investigated under nonlinear staged analysis. This is performed under two sections of constant temperature changes with four different temperatures as indicators of the spectrum from cold to tropical cities, and the seasonal changes in ambient conditions with real growth of creep curves and modulus of elasticity in four modes of the construction start at each of the four seasons of the year, giving indications of the long‐term behavior of high‐rise dual systems and special moment resisting frames. The structures are designed optimally, based on the results of the conventional one‐step analysis and regardless of inelastic strains and temperature effects. This ensures that after applying the concrete time‐dependent parameters at desired temperatures and redesigning according to new forces of nonlinear staged analysis, the feasibility of comparing changes in sections and drifts of the structures can be established. The results show that summer is the worst season to start construction.

Research on Fractal Characteristics and Energy Dissipation of Concrete Suffered Freeze-Thaw Cycle Action and Impact Loading

“…These mesoscopic damage structures gestate, develop and converge continuously under the outer loads, thus the broken blocks of concrete have a certain fractal characteristics. However, most existing studies focus on the static or the dynamic performance of concrete materials at normal temperature or high temperature [4,11,12,13,14,15,16,17,18], and there are relatively few researches on mechanical properties of concrete under the coupled action of impact loading and freeze-thaw cycles, and the representative studies mainly include: Sun introduced the damage of concrete under the simultaneous action of load and freeze-thaw cycle and its dependence on concrete of different strength grades [19]; Xiao conducted separated Hopkinson pressure bar (SHPB) tests on four kinds of ceramsite concrete with different volume content at different freezing-thawing cycle condition, and obtained the empirical formula of relative dynamic maximum stress of ceramsite concrete [20]. Nevertheless, none of the above studies takes into account the impact fracture fractal and energy dissipation characteristics of concrete materials under the coupled action of freeze-thaw cycle and impact loading.…”