ABSTRACT
In this paper, the significance of application-oriented fundamental research on concrete and reinforced concrete structures for progress regarding practical applications to structural design is addressed based on four examples. They were treated in a joint research project of Vienna University of Technology and Tongji University. The first topic refers to sudden heating or cooling of concrete structures, the second one to high-dynamic strength of specimens made of cementitious materials, the third one to structural analysis of segmental tunnel rings used in mechanized tunneling, and the fourth one to serviceability and ultimate limit states of concrete hinges used in integral bridge construction. The first two topics deal with exceptional load cases. Results from the fundamental research call for improvements of state-of-the-art simulation approaches used in civil engineering design. The last two topics refer to reinforced concrete hinges used in mechanized tunneling and integral bridge construction, respectively. Integrative research has led to progress regarding the verification of serviceability and ultimate limit states. In all four examples, results from fundamental research are used to scrutinize state-of-the-art approaches used in practical structural design of civil engineering structures. This allows for identifying interesting directions for the future development of design guidelines and standards.
ABSTRACT
A nonlinear hybrid method is developed for multiscale analysis of a bearing-capacity test of a real-scale segmental tunnel ring subjected to point loads. The structural analysis consists of two parts. Part I refers to modeling of bending-induced tensile cracking of the segments, resulting from the external loading. The segments are subdivided into elements, according to the crack spacing. Each element is either intact or contains one central crack band, flanked by lateral undamaged domains. A multiscale model for tensile softening of concrete is used to describe the progressive deterioration of the crack bands. After iterative determination of their state of damage, the effective bending and extensional stiffnesses of the corresponding elements are quantified by means of Voigt-Reuss-Hill estimates. The effective stiffnesses are used for linear-elastic simulations of the segmental tunnel ring. Part II refers to the relative rotation angles at the joints, which are estimated from monitoring data, using the Bernoulli-Euler hypothesis. Since the validity of this hypothesis is questionable for neck-like joints, the relative rotation angles are post-processed such that they refer to rigid body displacements of the segments. The following conclusions are drawn: The presented approach yields good estimates of crack widths. Relative rotation angles at the joints mainly result in rigid body displacements of the segments, governing the convergences. Because realistic interface models are lacking, hybrid analysis based on displacement-monitoring data allows for performing ultimate-load analysis of segmental tunnel rings.
