The use of steel concentrically braced frames (CBFs) has substantially increased recently. However, investigations and observations from past earthquakes suggest that some existing CBFs, particularly the older ones are still in service but were designed without ductile detailing compliance with state-of-the-art seismic provisions, may exhibit unfavorable performance during strong earthquake events. This research numerically examines adequacy a rehabilitation technology for deficient...

Existing steel concentrically braced frame (CBF) buildings subjected to seismic hazards can exhibit an undesirable soft-story response, in which drift and damage are concentrated a single story, whereas other stories remain relatively undamaged. This paper investigates the fundamental behavior proposes rehabilitative design procedure that uses stiff rocking core (SRC) redistribute lateral demands, thereby preventing response. The technique is nonintrusive compared traditional measures...

This paper investigates a seismic retrofit technique that allows bridge steel truss piers to uplift and rock on their foundation. Displacement-based passive energy dissipation devices (buckling-restrained braces, or BRBs) are implemented at the uplifting location control rocking response while providing additional dissipation. The hysteretic behavior of controlled system is developed for static cyclic load applied top pier, representing dominant mode vibration. Some existing methods analysis...

The conceptual design of an innovative seismic-resistant steel framing system capable providing stiffness and ductility to new or existing structures is presented. bracing consists concentric X-braces connected in series with rectangular sacrificial shear panels. braces are designed remain elastic during seismic events while the panels sized configured dissipate ample energy through plastic deformation-induced stable hysteretic behavior. Detailed three-dimensional nonlinear finite-element...

Shake table testing of a 1/5 scale model slender bridge steel truss pier that uses controlled rocking approach as means seismic protection was conducted. The allows the to uplift from its base while passive energy dissipation devices (steel yielding or fluid viscous dampers) are implemented across uplifting location control response. fundamental static and dynamic bidirectional behavior four-legged piers has been developed evaluated in past research. This paper discusses experimental...

The use of a stiff rocking core (SRC) has been proposed as seismic rehabilitation technique to mitigate soft-story response in low-rise midrise steel concentrically braced frame (CBF) structures. This uses stiff, elastic “spine” provide corrective lateral forces at the onset but otherwise remains passive for first mode vibration response. Yielding link element can also be incorporated SRC-to-structure connection dissipate energy and reduce overall building drift. An experimental testing...

This article focuses on evaluating the adequacy of a seismic rehabilitation technology which adds rocking cores to deficient steel concentrically braced frames in near-fault regions. Two demonstration buildings were rehabilitated with technology. Seismic performance was evaluated through numerical simulations. Analysis results suggest that code-compliant may be vulnerable collapse under fault-normal components ground motions, approximately having probability exceedance 10% 50 years. It is...

Seismic demands on steel building frames can result in concentrated inter-story drift and a "soft-story" mechanism multistory buildings which has led to severe structural damage or collapse past earthquakes. Such deficiencies structures be found seismic regions throughout the world are especially problematic developing countries. Furthermore, near an active fault may subjected near-fault ground motion pulses that have tendency induce very large, ductility lower stories of buildings. Economic...

This paper provides an overview of analysis performed on a new base isolation system developed for seismic steel pallet storage racks. Pallet racks are often found in warehousing material and designed to store materials pallets horizontal rows with multiple levels which accessed by forklift trucks. The the cross-aisle direction incorporating heavily damped elastomeric bearings (referred here as mounts) low-friction bearing plates. objective is reduce accelerations rack eliminate product...

Mitigation of Air-Blast Pressure Impulses on Building Envelopes through Blast Resistant Ductile Connectors Daniel Lavarnway, Michael Pollino Abstract The rise intentional or unintentional explosions both defense critical and conventional buildings requires development enhanced solutions for the blast protection structures. This study investigates use a simple, effective building envelope connector that provides an energy absorbing mechanism mitigating effects event onto building. application...

Fatigue demands often control design and detailing requirements of wind turbine support structures including the tubular steel tower. The in-situ structural placed on a community-scale (100kW) have been monitored for approximately one year fatigue quantified using Palmgren-Miner approach. A rain-flow counting method is used calculating stress range cycles during response. Demand-to-capacity ratios few common critical tower details are presented can be estimation remaining life. Future...

This paper focuses on investigation of a new seismic rehabilitation method to mitigate soft-story failures in deficient, multi-story, steel, concentrically braced frames (CBFs). The considered consists sufficiently stiff rocking core (RC) that is pinned the foundation and connected an existing deficient CBF building re-distribute forces along its height, creating more uniform inter-story drift ductility demand distributions. Two benchmark steel buildings - including one 3-story 6-story...

The behavior and design of four-legged controlled rocking bridge steel truss piers to three components seismic excitation are presented in this paper. approach for protection allows a pier uplift from its base, limiting the force demands placed on deck, can allow structure remain elastic during an earthquake, preventing damage toward goal keeping operational immediately following earthquake. Passive energy dissipation devices [steel yielding (SYDs) or fluid viscous dampers (VDs)] used at...

Performance-based seismic design has brought about innovative rocking and self-centering structural systems such as the controlled steel braced frame (CRBF). This lateral force resisting system recently received focused attention in academic research however seen limited application practice to date. may be due part unconventional load path plastic mechanisms formed during response. The transfer of forces through a CRBF with few configurations passivie energy dissipating devices (steel...

Controlled rocking of steel braced frames has been proposed for the seismic retrofit structures. The controlled approach allows a frame to uplift from its support at base-of-column foundation interface while displacement-based yielding devices are implemented base location control response. Past studies have focused on analytical investigations response such system along with design applications bridge piers. This paper discusses shake table testing 4-legged, pier representative 1/5 length...

Structural monitoring of a small wind turbine has been ongoing to measure the in-situ structural response turbine. The measurements provide valuable information for design, construction, and performance structures during normal operating extreme events. instrumentation includes strain gauges located on tower anchor bolts at two locations along height. bolt initial prestressing losses erection. In-service provides forces foundation, certain dynamic characteristics turbine, fatigue demand...

The rise of intentional or unintentional explosions, on both defense critical and conventional buildings, is domestic international concern requires the development enhanced, cost-effective solutions for blast protective design rehabilitation structures. This study explores feasibility a simple, building envelope connector that provides an energy-absorbing mechanism mitigating effects air-blast pressures onto from ground explosion. resistant ductile connectors (BRDC) are intended to be...