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Strain hardening behavior can be observed in steel fiber reinforced concretes under tensile loads. In this paper, a statistical micromechanical damage framework is presented for the strain hardening steel fiber reinforced concrete (SH-SFRC) considering the interfacial slip-softening and matrix spalling effects. With a linear slip-softening interface law, an analytical model is developed for the single steel fiber pullout behavior. The crack bridging effects are reached by averaging the contribution of the fibers with different inclined angles. Afterwards, the traditional snubbing factor is modified by considering the fiber snubbing and the matrix spalling effects. By adopting the Weibull distribution, a statistical micromechanical damage model is established with the fracture mechanics based cracking criteria and the stress transfer distance. The comparison with the experimental results demonstrates that the proposed framework is capable of reproducing the SH-SFRC’s uniaxial tensile behavior well. Moreover, the impact of the interfacial slip-softening and matrix spalling effects are further discussed with the presented framework.

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Objective: This paper aimed to investigate the molecular mechanisms associated with angiotensin-converting enzyme (ACE)-inhibitory peptide activity involved in vascular extracellular matrix (ECM) remodeling. Therefore, changes in collagen fibers, elastic fibers and laminin were assessed in the left common carotid artery (LCCA). Methods: We selected 10-week-old male spontaneously hypertensive rats to study the expression levels of matrix metalloproteinases (MMPs), transforming growth factor, angiotensin (Ang) II and nuclear factor (NF)-p65 in the wall of carotid arteries. Results: Compared to the control group, laminin expression was significantly increased (p < 0.05) in the vascular endothelium of the LAP (a homemade ACE-inhibitory peptide, named by ourselves) group, whereas the percentage of elastic/collagen fibers in the LCCA vascular area was significantly decreased (p < 0.0001) in the LAP group. Immune blots of MMP-2, MMP-9, NF-p65 and AngII were significantly reduced in the LCCA wall in the LAP group. Conclusion: Vascular ECM remodeling may be related to the inhibitory action of LAP on ECM deposition.