Failure of nonstructural components during an earthquake can cause widespread property damage, lead to lengthy downtime of the structure, and pose a life-safety threat to the occupants. Current code provisions aim to minimize the life safety threat by specifying lateral force demands and anchoring requirements. These code requirements are based on a simplified equation that does not fully consider the component attachment’s contribution to its overall dynamic response. Research suggests that the component attachment is an important parameter that determines its dynamic properties. Most analyses of the dynamic response of floor-anchored nonstructural components use an idealized single-degree-of-freedom system with a concentrated mass. Nonlinear behavior is included in the component force-displacement relations while the boundary conditions remain fixed based to the floor. Assuming a nonlinear behavior of the attachment changes the fixed-based boundary conditions and results in uplift at the base of the model. Models that include uplift at the base can be found for analysis of rocking structures and soil-structure interaction, but are rarely applied for analyzing nonstructural components. This dissertation focuses on acceleration-sensitive equipment and examines the attachment design of floor-anchored mechanical and electrical nonstructural components. The dissertation includes three parts. (i) An extensive experimental shaking-table test study of a nonstructural experimental model that is attached via several attachment designs to a concrete slab. The experimental results demonstrate that the selected attachment properties govern the boundary conditions of the nonstructural component and strongly influence its dynamic response. (ii) A mechanics-based numerical modeling approach for floor-anchored nonstructural components attached via steel channel connections. It defines a generalized analytical approach to estimate the force-displacement relations of the attachment and offers a simple approach for the engineer to estimate the contribution of the attachment design to the dynamic amplification of the component. (iii) A numerical study that examines the mechanics-based modeling approach with a wide range of input motions, component parameters, and attachment properties.

Earthquakes that have occurred recently across the globe in various countries including United States, Japan, New Zealand, Haiti, Turkey and Italy have brought into light the poor seismic performance of older-type, non-ductile concrete buildings. These buildings, mainly designed and constructed prior to 1980s, lack proper seismic detailing and may pose an unacceptably high seismic risk.

Non-ductile concrete buildings pose one of the greatest seismic safety problems in the world due to the large amount of old buildings constructed in earthquake prone regions. It is indicative that according to the Concrete Coalition and the California inventory project there are 16,000-17,000 of these buildings in high earthquake risk counties of California. Many of these buildings have high occupancies, including residential, commercial and critical services. In case of a severe earthquake, the severe damage or even collapse that could occur in these buildings could result in large number of casualties.

While engineers generally recognize that proactive steps are required to address the risk posed by these buildings, mitigation efforts are largely stymied by insufficient knowledge about the scale of the problem, insufficient tools to identify the truly dangerous buildings, high costs of strengthening, and owner resistance to pay for the strengthening with uncertain benefits. This study constitutes an effort to identify seismically hazardous concrete frame buildings through simplified methods that do not require complicated analysis.

Three idealized concrete frame buildings with different heights are used as archetypes. The study attempts to link the collapse performance of these buildings with various structural deficiencies that appear commonly in older construction practice. To evaluate the performance of these buildings non-linear dynamic analysis for several far-fault ground motions is performed. The analysis considers nonlinearities associated with flexural yielding, shear and axial failure. The main deficiencies explored are development of weak story mechanisms due to strong column-weak beam designs, brittle shear or axial failure modes associated with inadequate column shear reinforcement detailing, and splicing and connectivity weaknesses between structural members.

The results indicate that the suggested methods can be used to assess the collapse risk of older-type concrete buildings. The methods developed in the current study use simple engineering parameters such as column-to-beam strength ratio and column flexural to shear strength ratio to estimate the collapse risk of older type concrete buildings. A probabilistic approach is suggested that takes into account record-to-record variability and could accommodate as well uncertainty associated with structural properties and collapse modeling.

In Chapter 7 the proposed methodology is evaluated by applying it to the three idealized buildings developed. The estimated probabilities of collapse calculated for each of the buildings according to the proposed methodology are compared with the values provided by sophisticated non-linear dynamic analyses. The results suggest that the proposed methodology successfully identifies deficiencies that are leading to high collapse potential and provides an effective tool in classifying collapse prone concrete frame buildings.