مقاله انگلیسی رایگان در مورد فرسودگی بتن تقویت شده با الیاف – الزویر ۲۰۱۹

High performance fiber reinforced concrete (HPFRC) is recognized as suitable material for structural applications. The number of national codes that have approved it is an evidence. Structures where HPFRC is generally used can be subjected to fatigue loads and are expected to resist millions of cycles during their service life. Cyclic loads affect significantly the characteristics of materials and can cause fatigue failures. The most demanded cross-sections being cracked under tensile stresses due to direct loads or imposed deformations. Commonly, publications report fatigue behavior of concrete under compression and are valid for uncracked sections. Imprecision in fatigue prescriptions are reflected through formulation of models that contemplate a probabilistic approach, or introduction of high safety coefficients within construction codes. The aim of the present research is to perform a structural design oriented analysis on the behavior of pre-cracked HPFRC subjected to flexural fatigue loads. Seven load levels were applied by means of three-point bending tests, considering an initial crack width accepted in the service limit state. Results showed that the monotonic load-crack opening displacement curve might be used as deformation failure criterion for HPFRC under flexural fatigue loading. The conducted probabilistic approach allows predicting the fatigue strength of HPFRC cracked sections.

Introduction

Fiber reinforced concrete (FRC) and high performance fiber reinforced concrete (HPFRC) are recognized as suitable materials for structural applications such as tunnel linings [1], pavements [2], highway or bridge decks overlays [3,4], wind energy towers [۵,۶], offshore structures [7,8] seismic resistant structures [9,10] and for the repair of old structures and infrastructure facilities [11]. These structures can be subjected to cyclic loads and these are expected to resist millions of cycles during their service life. The most demanded cross-sections of these structures being cracked under tensile stresses due direct loads or imposed deformations (e.g., thermal-hygrometric induced stresses, differential settlements). Cyclic loads affect significantly the characteristics of materials (strength, stiffness, toughness, durability, etc.) even under service loads [12,13] and could lead to fatigue failures. Recommendations, technical reports and guidelines on fatigue in (ultra) high performance concrete are available, such as the State-of-art report from the American Federal Highway Administration [14], the Japan Recommendations for Design and Construction of High Performance Fiber Reinforced Cement Composites [15], the fib Model Code 2010 [16], which covers concrete up to 120 MPa, the DNV GL standard [17], the French standards [18,19], and the draft of the German guideline [20].