中速动态加载条件下的混凝土断裂试验研究.docVIP

  Experimental Investigation of concrete under Moderate Dynamic Loading# 5 10 15 20 25 30 35 40 DONG Lixin1,3, XU Shilang2** (1. Faculty of Construction Engineering, Dalian University of Technology,116024; 2. School of Architecture and Engineering, Zhejiang University, 310058; 3. School of Civil Engineering, Jilin Jianzhu University,130118) Abstract: This paper presents the recent results of experimental investigations under dynamic loading aimed at disclosing the loading rate effect (mainly related to seismic loading range) on crack propagation in quasi-brittle fracture. Twenty four wedge-splitting tests were conducted using a servo-hydraulic machine under loading rates ranged from 0.001 mm/s to 10 mm/s. Strain gauges were mounted along the ligament of the specimen to measure the crack velocity and the crack propagation. Several important results were gained through the experimental investigations in this paper Key words: dynamic loading rate；crack propagation；quasi-brittle fracture；seismic loading range 0 Introduction Dynamic loading on concrete structures arising from earthquakes is a topic of great practical concern. Researches during the last three decades have shown that the rate dependency of the concrete strength tends from a moderate rate dependency to excessive rate effects at high loading rates [1]. In comparison to other rate dependent materials, concrete exhibits its rate dependency at relatively low loading rates because of a 10-3m length scale of the heterogeneity [2,3,4]. It has been confirmed by studies that the time-dependence is caused by three different effects (1) the rate dependent bond-breakage process which produces the fracture surfaces, (2) the viscous behavior of the bulk material between the cracks and (3) the inertia effect in the neighborhood of the crack tip, which can significantly change the state of stresses and strains of the material [5,6,7,8,9]. As far as the seismic loading rate (ranged from 10-4s-1 to 10-1s-1) is concerned