Richard Sause

Seismic Performance of a Large-Scale Steel Self-Centering Moment-Resisting Frame: MCE Hybrid Simulations and Quasi-Static Pushover Tests

AbstractThis paper presents an experimental study of a 0.6-scale 2-bay 4-story steel self-centering moment-resisting frame (SC-MRF) test structure under maximum considered earthquake (MCE) ground motions. A SC-MRF uses high-strength posttensioning (PT) strands to precompress the beams to the columns and to close the gaps between the beam flanges and column flanges that occur at the beam-column interface under earthquake loading, returning the frame to its initial position (i.e., the frame is self-centering). In this study, a beam web friction device is included in each beam-column connection to dissipate energy under seismic loading. The SC-MRF design objectives are to be without structural damage, creating the potential for immediate occupancy performance under the design basis earthquake, and to suffer only modest damage, leading to collapse prevention (CP) performance under the MCE. The CP performance is achieved by avoiding beam web buckling and PT strand yielding and fracture. A special fuse that pre...

Time-Dependent Reliability of PSC Box-Girder Bridge Considering Creep, Shrinkage, and Corrosion

Bridge performance undergoes time-varying changes when exposed to aggressive environments. While much work has been done on bridge reliability under corrosion, little is known about the effects of creep and shrinkage on the reliability of concrete bridges. In this paper, the CEB-FIP model for creep and shrinkage is applied by using finite-element (FE) analysis in conjunction with probabilistic considerations. Verification is made by comparing the analytical findings with existing test data. More specifically, a time-dependent reliability assessment is made for a composite prestressed concrete (PSC) box-girder bridge exposed to a chloride environment. This realized via an advanced probabilistic FE method. The postcracking behavior of the thin-walled box girder is described using composite degenerated shell elements, and importance sampling is used to improve the efficiency of the reliability analyses. It is shown that concrete creep and shrinkage dominate during the early stages of bridge structure deterio...

Integrated Analytical and Experimental Research to Develop a New Seismic Design Methodology for Precast Concrete Diaphragms

AbstractA new seismic diaphragm design methodology has been developed for precast concrete floor diaphragms. The knowledge required to create the design methodology was obtained through an integrated analytical and experimental research project using two Network for Earthquake Engineering Simulation (NEES) equipment sites. The activities of the project involved a sequence of integrated research tasks that systematically developed knowledge about diaphragm behavior from the reinforcement detail level to the structural system level. These tasks included the use of state-of-the-art experimental techniques made possible through the NEES facilities including hybrid simulation and large-scale shake table tests. Such techniques were crucial to the research as the complex behavior of precast diaphragms is not well described by simple analytical models or idealized experiments. Valuable industry oversight in the planning, execution, and technology transfer stages of the project guided the research activities, incl...

Fatigue Performance of Stiffened Pole-to-Base Plate Socket Connections in High-Mast Structures

AbstractFatigue performance of stiffened pole-to-base plate socket connection in high-mast lighting structures was evaluated by experimental and analytical studies. In absence of sufficient experimental data, constant amplitude fatigue limit (CAFL) of longitudinal stiffener terminations on pole walls is classified as Category E′ in the existing American Association of State Highway and Transpiration Officials (AASHTO) specification. Fatigue performance of this connection in the thin-walled tubular structures is controlled by localized secondary bending stress, the magnitude of which depends on the relative stiffness of the connecting elements. Ten full-size high-mast specimens having stiffened socket connection were tested under constant amplitude reversal loading to determine the fatigue resistance of this connection in finite and infinite life regimes. The specimen design was optimized by parametric finite-element analysis (FEA) and local stress approaches. FEA results were verified by conducting static...