Abstract Research engineers use two types of energy equations to study single‐degree‐of‐freedom (SDOF) systems subject earthquake induced ground motions. The first method uses an absolute formulation; the second a relative formulation. While formulation has been used in majority previous investigations, this shows that equation is physically more meaningful. For given ductility ratio, input demands calculated by both methods are significantly different for short and long period ranges...

The seismic performance of a posttensioned energy dissipating (PTED) connection for steel frames is investigated analytically and experimentally. PTED incorporates high-strength bars to provide self-centering response along with that are able yield in axial tension compression. analytical study involves the development an equivalent iterative sectional analysis procedure predict moment-rotation relationship connection. Based on this model, simple design connections described. In experimental...

This paper derives the basic formulas for establishing response modification factor R and displacement amplification Cd used in National Earthquake Hazards Reduction Program (NEHRP) recommended provisions. An extension of approach is to derive system Rw 1988 Uniform Building Code. These terms are primarily functions both structural overstrength ductility factors. Because empirical nature NEHRP values these factors, it difficult justify relative between factors most building systems. The...

Tests were conducted on two prototype steel shear links for the main tower of new San Francisco-Oakland Bay self-anchored suspension bridge to evaluate link force and deformation capacities. The built-up wide-flange sections, designed yield in shear. A quasi-static loading protocol was used test reverse curvature, simulating expected seismic demand. capacities exceeded predicted demands from Safety Evaluation Earthquake. specimens behaved a ductile manner until small cracks initiated at end...

The effectiveness of using the reduced beam section (RBS) and welded haunch for seismic rehabilitation pre-Northridge steel moment connections was investigated through cyclic testing six full-scale specimens—three them incorporated lightweight concrete slabs. Test results showed that, unless low-toughness E70T-4 groove weld replaced by notch-tough metal, introducing RBS to bottom flange alone could not prevent brittle fracture in top flange. presence a slab or removing backing only improved...

The inelastic rotation capacity of links in eccentrically braced frames (EBFs) is dependent on testing loading history or sequence. Current design rotations for are based experiments from the 1980s performed with somewhat arbitrary protocols. An AISC link protocol, derived standard moment frame has been used since 2002. This protocol results lower capacities. Since no previous current protocols EBF analyses, nonlinear time-history analyses were conducted to investigate cumulative demands...

Design engineers frequently use deep columns in steel special moment resisting frames to control drift. As the reduced beam section (RBS) connection is becoming popular after 1994 Northridge, California earthquake, SAC Joint Venture initiated a testing program study cyclic behavior of deep-column RBS connections. The test results showed that column prone twisting. twisting was caused by eccentric flange force due lateral-torsional buckling beam. In this paper, cycle tests three connections...

An analytical study was conducted to investigate the influence of flange width–thickness ratio on rotation capacity links in eccentrically braced frames. Finite element models, verified using experimental data, were used performance 112 links. Models simulated strength degradation associated with and web local buckling that may occur during cyclic loading. The models provided data for short, intermediate, long a range ratios. Results indicate relaxation requirement current AISC seismic...

Fatigue tests of full-scale orthotropic steel decks were recently conducted to evaluate the fatigue performance rib-to-deck partial-joint-penetration (PJP) groove welded joints. The test results indicated that joints are more prone cracks in deck plate than rib wall. A shallower weld penetration (for example, an 80% PJP) also appeared have a slightly higher resistance deeper one 100% penetration). These PJP welds vulnerable cracking initiated from toe root. Finite-element analyses specimens,...

During an earthquake, steel braced frame columns can be subjected to high axial forces combined with inelastic rotation demand resulting from story drift. Cyclic testing of nine full-scale W14 column specimens representing a practical range flange and web width-to-thickness ratios were different levels force (35, 55, 75% nominal yield strength) up 10% No global buckling was observed in all test specimens. Flange local the dominant mode. Specimens achieved interstory drift capacities 0.07–...

Flexural tests on full-scale I-shaped beams, built up from high-strength steels (HSB800 and HSA800) with a nominal tensile strength of 800 MPa, were carried out to study the effect flange slenderness flexural rotation capacity. The primary objective was investigate appropriateness extrapolating current stability criteria (originally developed for ordinary steel) steel. For comparison purposes, specimens steel (SM490) also tested showed sufficient capacity in accordance AISC specification....

This state-of-the-art review provides an overview of the evolution seismic design requirements for main steel building force–resisting systems, as driven by new developments, 1994 Northridge, California, earthquake, and changes in earthquake engineering practice United States. Important aspects these systems terms ductility capacity are highlighted. Recent developments related to innovative touched upon. The work presented here is intended provide reader with appreciation why current...

ABSTRACT Steel moment frames composed of wide‐flange steel members are commonly used in seismic regions, with deep and slender column sections often selected to economically satisfy drift limit requirements. The section slenderness makes the columns more susceptible local global buckling subsequent axial shortening when subjected combined high forces lateral deformations. Numerous tests have been conducted on individual under a wide range loads loading patterns. Experimental data subassembly...

This paper presents test results on eight reduced beam section (RBS) steel moment connections. The testing program addressed web connection type (bolted versus welded) and panel zone (PZ) strength as the key variables. Specimens with medium PZ were designed to promote energy dissipation from both RBS regions such that expensive doubler plates not needed. Both strong specimens a welded able provide satisfactory rotation capacity for special moment-resisting frames. However, bolted performed...

Abstract Energy serves as an alternative index to response quantities like force or displacement include the duration‐related seismic damage effect. A procedure evaluate absorbed energy in a multistorey frame from spectra was developed. For low‐ medium‐rise frames, it required static pushover analysis of structure determine modal yield and ductility factor equivalent single‐degree‐of‐freedom system for first two modes. The were then used contribution each mode. also developed distribute...

ABSTRACT Shake table tests were undertaken on an actual wind turbine (65 kW rated power, 22.6 m hub height and a 16 rotor diameter) using the Network for Earthquake Engineering Simulation Large High Performance Outdoor Table at University of California, San Diego. Each base shaking event was imparted in two states, whereas still (parked), while it spinning (operational). state tested orientations direction, one parallel (fore‐aft) another perpendicular (side‐to‐side) to axis rotation rotor....

As part of a National Institute Standards and Technology (NIST) comprehensive research program to study the seismic behavior design deep, wide-flange structural steel beam-column members for application in construction special moment frames, 25 deep column specimens were subjected inelastic cyclic loading with three different levels constant compression axial load (Ca = 0.2, 0.4 0.6). The test matrix included five W24 sections (W24×55 W24×176) cover wide range element slenderness ratios...

This paper describes a design procedure for the seismic rehabilitation of pre-Northridge steel moment connections using welded haunch. Experimental results from cyclic testing full-scale specimens demonstrated that welding triangular haunch beneath beam's bottom flange significantly improved performance connections. The drastically changed beam shear force transfer mechanism, which assisted in reducing demands at groove welds. Analytical studies further showed tensile stress existing weld...

Standard construction 2.4m×2.4m woodframe shearwalls were tested using different loading protocols. The CUREE-Caltech protocols, recently developed by Krawinkler in 2001, compared with other previously used following protocols considered the study: monotonic, standard (CUREE), near-fault, sequential phased displacement (SPD), and international standards organization. Findings from research indicate that sequence has a significant influence on shearwall performance. Protocols large number of...

For energy-based seismic design, energy demand in the form of absorbed spectra was established by an attenuation relationship. The is proposed for evaluating inelastic system because directly related to pseudo-velocity elastic case. Based on a total 273 ground motion records from 15 significant earthquakes California, relationship two-stage non-linear regression analysis. This given earthquake magnitude, source-to-site distance, site class, and ductility factor. A similar expression...

In a study of previous weak-axis moment connection tests it was noticed that the most common failure mode brittle fracture initiating near edge beam flange groove weld. The cause large stress concentrations due to force flow towards stiffer column flanges, which is opposite pattern as strong-axis connections. As part SAC (a partnership SEAoC, ATC, and CUREE) study, two full-scale connections, utilizing reduced section (RBS) design, were statically tested under simulated seismic loading. Both...

A common practice for the fabrication of steel orthotropic bridge decks in United States is to use 80% partial joint penetration (PJP) groove welds between closed ribs and deck plate. However, it difficult eliminate weld melt-through with thin rib plates. Heat straightening after welding, sometimes combined precambering, used meet plate flatness requirement. To study effects both distortion control measures on fatigue resistance rib-to-deck welded joint, six full-scale two-span specimens...