Robust power law extrapolation for adhesive anchors under sustained load

Post-installed adhesive anchors play an important role in modern construction. As with many structural products, adhesive anchors must undergo rigorous testing to verify serviceability and ultimate performance characteristics under job-site-relevant conditions before being used in real projects. The check of long-term performance under sustained load is based on extrapolation from experimental short-term creep data approximating the creep mechanism of the entire anchor system with a power law model as detailed, for example, in ACI 355.4 and ETAG 001. These normative guidelines are critically reviewed from a scientific as well as practical point of view. Based on the presented evidence, specific recommendations for anchor testing and assessment guidelines are proposed

Design for lifecycle robustness of fastening systems

The future requirements on faster and automated construction, improved life-cycle performance and sustainability of infrastructure in general increasingly promote the use of fastening technology. This paper addresses the concept of lifecycle robustness by introducing an ensemble of technical and management measures, covering the entire life span from design, construction, operation and decommissioning. Although a significant research on robustness and performance indicators has been performed in related areas, such as bridges or nuclear power plants, a framework for the quantification of lifecycle robustness of fastening systems is still not available. The presented proposals are based on the synthesis of theoretical and technological progress, established engineering design approaches and communication procedures, and experimental evidence, all originating from in-house research and industrial partners. Rather than discussing particular technical aspects, this paper focuses on the uncertainty management and hazard mitigation policies through the entire life span of the fastening systems

Inherent Variability of Lattice Discrete Particle Models Caused by Particle Placement Strategies

The paper aims at characterizing the influence of particle placement and clustering in lattice discrete particle models (LDPM) on structural response. More specifically, the meso-structural features are mimicked by the proposed particle placement schemes for LDPM, which are no longer independent and random but are correlated to prescribed fields. The study is based on high-dimensional Monte Carlo (MC) LDPM simulations of three classical concrete tests in which the inherent variability and production process are represented by the proposed particle placement schemes with varying parameters, and constant material and composition properties

Evolution of creep and shrinkage models for concrete structures in Austria and Germany : evaluation of the current models regarding the sensitivity of the input parameter

Evolution of creep and shrinkage models for concrete structures in Austria and Germany - Evaluation of the current models regarding the sensitivity of the input parameter Concrete is one of the most important materials in civil engineering structures and finds its application in the building of bridges, ground engineering and building construction. As widely known, concrete is a material which changes its behavior with time in dependency of the environmental conditions. Especially the long-term deformations caused by creep and shrinkage processes are of great interest regarding the durability and sustainability of infrastructures. Early versions of design codes gave some guidelines on how to treat deformations caused by these sources. In the beginning, these deformations were taken into account by an additional temperature drop. The first sophisticated approaches on how to deal with these long-term processes were published in the standards for prestressed concrete structures. These early models were updated and improved to today's prevailing documents such as the Eurocode 2 and the fib Model Code. The first part of this paper gives an overview of the historical development of creep and shrinkage models in Austria and Germany until today's guidelines. The second part presents a sensitivity study of the current models regarding the input parameters for some given scenarios. Lastly, the differences between the models are highlighted based on an application example taken from literature