flexural response
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2021 ◽  
Author(s):  
Juliette Grosset ◽  
Stéphane Mazzotti ◽  
Philippe Vernant

Abstract. The understanding of the origins of seismicity in intraplate regions is crucial to better characterize seismic hazards. In formerly glaciated regions such as Fennoscandia North America or the Western Alps, stress perturbations from Glacial Isostatic Adjustment (GIA) have been proposed as a major cause of large earthquakes. In this study, we focus on the Western Alps case using numerical modeling of lithosphere response to the Last Glacial Maximum icecap. We show that the flexural response to GIA induces present-day stress perturbations of ca. 1–2 MPa, associated with horizontal extension rates up to ca. 2.5 × 10−9 yr−1. The latter is in good agreement with extension rates of ca. 2 × 10−9 yr−1 derived from high-resolution geodetic (GNSS) data and with the overall seismicity deformation pattern. In the majority of simulations, stress perturbations induced by GIA promote fault reactivation in the internal massifs and in the foreland regions (i.e., positive Coulomb Failure Stress perturbation), but with predicted rakes systematically incompatible with those from earthquake focal mechanisms. Thus, although GIA explains a major part of the GNSS strain rates, it tends to inhibit the observed seismicity in the Western Alps. A direct corollary of this result is that, in cases of significant GIA effect, GNSS strain rate measurements cannot be directly integrated in seismic hazard computations, but instead require detailed modeling of the GIA transient impact.


2021 ◽  
Vol 9 (4B) ◽  
Author(s):  
Maninder Singh ◽  
◽  
Babita Saini ◽  
H.D. Chalak ◽  
◽  
...  

The addition of supplementary cementitious materials and fiber plays an important role in the mechanical and durability performance of ECC matrix. In the present research work, the assessment of the performance of ECC matrix with the utilization of iron industry waste and microfibers has been done. Three types of microfibers, i.e., polyvinyl alcohol (PVA) fiber, polyester (PET) fiber, and microsteel (MSE) fiber, were used at various percentages in hybridization to prepare total seven mixes. First, PVA was switched by PET fiber at dosages 5%, 10%, 15%, 20%,and 25% and afterwards another 25% by MSE fiber. The performance of various matrix proportions was judged based on the flexural response, electrical resistivity, air permeability, and sorptivity characteristics to introduce sustainable and cost effective ECC matrix. Test results revealed that hybridization of fibers enhanced the flexural and durability performance of ECC and also produced a cost effective and sustainable ECC matrix.


Structures ◽  
2021 ◽  
Vol 34 ◽  
pp. 589-603
Author(s):  
Khondaker Sakil Ahmed ◽  
Md Ahsan Habib ◽  
Md Farhan Asef

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7349
Author(s):  
Ahmed Bahgat Tawfik ◽  
Sameh Youssef Mahfouz ◽  
Salah El-Din Fahmy Taher

The numerical simulation of concrete fracture is difficult because of the brittle, inelastic-nonlinear nature of concrete. In this study, notched plain and reinforced concrete beams were investigated numerically to study their flexural response using different crack simulation techniques in ABAQUS. The flexural response was expressed by hardening and softening regime, flexural capacity, failure ductility, damage initiation and propagation, fracture energy, crack path, and crack mouth opening displacement. The employed techniques were the contour integral technique (CIT), the extended finite element method (XFEM), and the virtual crack closure technique (VCCT). A parametric study regarding the initial notch-to-depth ratio (ao/D), the shear span-to-depth ratio (S.S/D), and external post-tensioning (EPT) were investigated. It was found that both XFEM and VCCT produced better results, but XFEM had better flexural simulation. Contrarily, the CIT models failed to express the softening behavior and to capture the crack path. Furthermore, the flexural capacity was increased after reducing the (ao/D) and after decreasing the S.S/D. Additionally, using EPT increased the flexural capacity, showed the ductile flexural response, and reduced the flexural softening. Moreover, using reinforcement led to more ductile behavior, controlled damage propagation, and a dramatic increase in the flexural capacity. Furthermore, CIT showed reliable results for reinforced concrete beams, unlike plain concrete beams.


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7203
Author(s):  
Ibrahim A. Sharaky ◽  
Ahmed S. Elamary ◽  
Yasir M. Alharthi

It is essential to make openings in structural concrete elements to accommodate mechanical and electrical needs. To study the effect of these openings on the performance of reinforced concrete (RC) elements, a numerical investigation was performed and validated using previous experimental work. The effect of the position and dimension of the opening and the beam length on the response of the beams, loads capacities, and failure modes was studied. The simulated RC beams showed different responses, loads capacities, and failure modes depending on the position and dimension of the opening. The transversal near support opening (TNSH) and longitudinal holes (LH) showed lower effects on the load capacities of the beams than the transversal near center opening (TNCH). The supreme reduction percentages of the load capacity (µu%) for beams with TNCH and TNSH were 37.21% and 30.34%, respectively (opening size = 150 × 150 mm2). In addition, the maximum µu% for beam with LH was 17.82% (opening size = 25% of the beam size). The TNSH with a width of less than 18.18% of the beam shear span (550 mm) had trivial effects on the beam’s load capacities (the maximum µu% = 1.26%). Although the beams with combined LH and TNCH or LH and TNSH showed different failure modes, they experienced nearly the same load reductions. Moreover, the length of the beam (solid or hollow) had a great effect on its failure mode and load capacity. Finally, equations were proposed and validated to calculate the yield load and post-cracking deflection for the concrete beams with a longitudinal opening.


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