Interactive educational models for structural dynamics

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.Includes bibliographical references (p. 85-86).by Gilberto Mosqueda.M.S

Effects of Cold-formed Steel Framed Gypsum Partition Walls on the Seismic Response of a Medical Facility

The first experimental phase of the NEES Nonstructural Grand Challenge Project: “Simulation of the Seismic Performance of Nonstructural Systems” investigated the in-plane hysteretic behaviors of thirty-six full-scale cold-formed steel framed gypsum partition walls. Results of quasi-static reverse cyclic and dynamic testing on sixteen wall configurations including walls with commercial and institutional construction details and innovative connection techniques are first briefly reviewed. Thereafter, six tri-linear hysteretic models of partition walls with pinching behavior and strength and stiffness degradation are developed based on the experimental data for use in a finite element analysis platform. The partition wall models, represented by shear spring elements at each floor level, are incorporated into a numerical model of a four story steel moment frame medical facility. Although nonstructural components are required to carry self-imposed loads and minimal external loads and are not required to be considered in the structural analysis and design of buildings, the addition of the partition walls are shown to increase the stiffness and strength of the building, reducing the natural period by more than 11%. Furthermore, partition walls are shown to introduce over 42% more damping into the building due to the continual energy dissipation through their pinched hysteretic behaviors. The effect of the nonstructural partition walls on the inter-story displacements and absolute accelerations is also examined

Seismic Performance of a Special Steel Moment-Resisting Frame Subassembly from the Onset of Damage through Collapse

Although a wealth of knowledge on the behavior of steel moment frame structures has been gained from past experimental studies, there are only a limited number of system-level tests examining seismic response near collapse. Such experimental data is essential to validate and improve analytical tools that generally rely on empirical and mechanical component-level models to capture the global system behavior. In view of the limited experimental data, a series of tests were conducted at the Network for Earthquake Engineering Simulation equipment site at the University at Buffalo. Hybrid simulation with substructuring was employed as a cost-effective alternative for large-scale system-level testing of large subassemblies. The ½-scale specimen, consisting of a 1½-bay by 1½-story subassembly, was designed to capture the behavior and interactions of beams, columns, panel zones, and the composite floor slab. The experimental setup permitted the application of lateral as well as varying vertical forces on the test specimen while maintaining realistic boundary conditions on the subassembly. This paper presents a description of the seismic performance of the different components of the tested subassembly

Experimental investigation of steel building gravity framing systems under strong earthquake shaking

Hybrid simulations were conducted to evaluate the system-level seismic response of a 4-story steel moment frame building and its gravity framing system through various levels of ground motion shaking. The experimental substructure examined in detail corresponds to a half-scale 1½-bay by 1½-story subassembly of the steel gravity frame. Unlike typical beam-to-column connection tests, the subassembly, which represented typical gravity framing steel construction, captured the redistribution of force demands in beams, columns, panel zones, and the composite floor slab while exhibiting inelastic behavior. Horizontal as well as varying vertical forces were applied on the test specimen to mimic realistic boundary and loading conditions. This paper focuses on the experimental response of the gravity framing system and its contribution to the lateral resistance of a steel frame building. In particular, the lateral resistance and failure mechanisms of the test frame are described and compared to numerical simulations based on state-of-the-art modeling approaches. The data generated from these experiments provides valuable insight on gravity frame behavior towards improvement and verification of frame models at the system level

Observations About the Seismic Response of RC Buildings in Mexico City

Over 2000 buildings were surveyed by members of the Colegio de Ingenieros (CICM) and Sociedad Mexicana de Ingenieria Estructural (SMIE) in Mexico City following the Puebla-Morelos Earthquake of 2017. This inventory of surveyed buildings included nearly 40 collapses and over 600 buildings deemed to have structural damage. Correlation of damage with peak ground acceleration (PGA), peak ground velocity (PGV), predominant spectral period, building location, and building properties including height, estimated stiffness, and presence of walls or retrofits was investigated for the surveyed buildings. The evidence available suggests that (1) ground motion intensity (PGV) drove the occurrence of damage and (2) buildings with more infill and stiff retrofit systems did better than other buildings

Degradación y tolerancia de tolueno por pseudomonas putida dot-t1e

Universidad de Granada, Departamento de Bioquímica y Biología Molecular. Leída 24-03-0

Innovative substructuring technique for hybrid simulation of multistory buildings through collapse

Hybrid simulation combines numerical and experimental methods for cost-effective, large-scale testing of structures under simulated dynamic earthquake loads. Particularly for experimental seismic collapse simulation of structures, hybrid testing can be an attractive alternative to earthquake simulators due to the limited capacity of most facilities and the difficulties and risks associated with a collapsing structure on a shaking table. The benefits of hybrid simulation through collapse can be further enhanced through accurate and practical substructuring techniques that do not require testing the entire structure. An innovative substructuring technique for hybrid simulation of structures subjected to large deformations is proposed to simplify the boundary conditions by overlapping the domains between the numerical and experimental subassemblies. The advantages of this substructuring technique are the following: it requires only critical components of the structure to be tested experimentally; it reduces the number of actuators at the interface of the experimental subassemblies; and it can be implemented using typically available equipment in laboratories. Compared with previous overlapping methods that have been applied in hybrid simulation, this approach requires additional sensing in the hybrid simulation feedback loop to obtain internal member forces, but provides significantly better accuracy in the highly nonlinear range. The proposed substructuring technique is verified numerically and validated experimentally, using the response of a four-story moment-resisting frame that was previously tested to collapse on an earthquake simulator

Enhanced Seismic Protection System for an Emergency Diesel Generator Unit

Nuclear power plants are required to maintain operation after an earthquake, leading to a safe shutdown if necessary. In the case of a loss of offsite power, the onsite emergency diesel generator is critical to ensure procedural operations of the nuclear power plant. As a means to reduce the overall seismic risk, a three-dimensional seismic protection system is proposed to enhance the seismic performance of the emergency diesel generator. The proposed seismic isolation system decouples the horizontal and vertical components of shaking and considers available hardware to achieve an effective isolation solution over the range of excitation frequencies considered. Numerical analysis of the proposed system demonstrates a reduction in seismic demands on the emergency diesel generator and provides a higher safety margin than conventional base installation procedures. Umbilical lines that cross the isolation plane are considered and impose additional constraints on the displacement capacity of the isolation system. However, increasing the displacement capacity of these components can significantly increase the safety margin against failure. The seismic protection system can be customized depending on the seismic hazard and application to different seismic regions