scholarly journals Near-Source Ground Motion and its Effects on Flexible Buildings

1995 ◽  
Vol 11 (4) ◽  
pp. 569-605 ◽  
Author(s):  
John F. Hall ◽  
Thomas H. Heaton ◽  
Marvin W. Halling ◽  
David J. Wald
Keyword(s):  
Source Region ◽  
Nonlinear Behavior ◽  
Ground Shaking ◽  
Collapse Potential ◽  
Blind Thrust ◽  
Frame Buildings ◽  
Steel Frame Buildings ◽  
Blind Thrust Fault ◽  
Large Earthquakes ◽  
Strong Ground

Occurrence of large earthquakes close to cities in California is inevitable. The resulting ground shaking will subject buildings in the near-source region to large, rapid displacement pulses which are not represented in design codes. The simulated Mw7.0 earthquake on a blind-thrust fault used in this study produces peak ground displacement and velocity of 200 cm and 180 cm/sec, respectively. Over an area of several hundred square kilometers in the near-source region, flexible frame and base-isolated buildings would experience severe nonlinear behavior including the possibility of collapse at some locations. The susceptibility of welded connections to fracture significantly increases the collapse potential of steel-frame buildings under strong ground motions of the type resulting from the Mw7.0 simulation. Because collapse of a building depends on many factors which are poorly understood, the results presented here regarding collapse should be interpreted carefully.

Nonlinear behavior of soil sediments identified by using borehole records observed at the Ashigra Valley, Japan

1995 ◽  
Vol 85 (6) ◽  
pp. 1821-1834
Author(s):  
Toshimi Satoh ◽  
Toshiaki Sato ◽  
Hiroshi Kawase
Keyword(s):  
Shear Strain ◽  
Main Part ◽  
Nonlinear Behavior ◽  
Strong Motion ◽  
S Wave ◽  
Ground Shaking ◽  
Wave Velocities ◽  
The One ◽  
Soil Sediments ◽  
Strong Ground

Abstract We evaluate the nonlinear behavior of soil sediments during strong ground shaking based on the identification of their S-wave velocities and damping factors for both the weak and strong motions observed on the surface and in a borehole at Kuno in the Ashigara Valley, Japan. First we calculate spectral ratios between the surface station KS2 and the borehole station KD2 at 97.6 m below the surface for the main part of weak and strong motions. The predominant period for the strong motion is apparently longer than those for the weak motions. This fact suggests the nonlinearity of soil during the strong ground shaking. To quantify the nonlinear behavior of soil sediments, we identify their S-wave velocities and damping factors by minimizing the residual between the observed spectral ratio and the theoretical amplification factor calculated from the one-dimensional wave propagation theory. The S-wave velocity and the damping factor h (≈(2Q)−1) of the surface alluvial layer identified from the main part of the strong motion are about 10% smaller and 50% greater, respectively, than those identified from weak motions. The relationships between the effective shear strain (=65% of the maximum shear strain) calculated from the one-dimensional wave propagation theory and the shear modulus reduction ratios or the damping factors estimated by the identification method agree well with the laboratory test results. We also confirm that the soil model identified from a weak motion overestimates the observed strong motion at KS2, while that identified from the strong motion reproduces the observed. Thus, we conclude that the main part of the strong motion, whose maximum acceleration at KS2 is 220 cm/sec2 and whose duration is 3 sec, has the potential of making the surface soil nonlinear at an effective shear strain on the order of 0.1%. The S-wave velocity in the surface alluvial layer identified from the part just after the main part of the strong motion is close to that identified from weak motions. This result suggests that the shear modulus recovers quickly as the shear strain level decreases.

The identification of building structural systems

1976 ◽  
Vol 66 (1) ◽  
pp. 125-151
Author(s):  
Firdaus E. Udwadia ◽  
Panos Z. Marmarelis
Keyword(s):  
Nonlinear Behavior ◽  
Strong Motion ◽  
Ambient Vibration ◽  
Structural Systems ◽  
Reinforced Concrete Structure ◽  
Earthquake Excitation ◽  
Ground Shaking ◽  
Ambient Vibration Testing ◽  
Suitable System ◽  
Strong Ground

abstract This paper investigates the response of structural systems to strong earthquake ground shaking by utilizing some concepts of system identification. After setting up a suitable system model, the Weiner technique of nonparametric identification has been introduced and its experimental applicability studied. The sources of error have been looked into and several new results have been presented on accuracy calculations stemming from the various assumptions in the Wiener technique. The method has been applied in studying the response of a 9-story reinforced concrete structure to earthquake excitation as well as ambient vibration testing. The linear contribution to the total roof response during strong ground shaking has been identified, and it is shown that a marked nonlinear behavior is exhibited by the structure during the strong-motion portion of the excitation.

scholarly journals Past earthquake timing and magnitude along the Inglewood fault, Taranaki, New Zealand

1994 ◽  
Vol 27 (2) ◽  
pp. 155-162 ◽  
Author(s):  
A. G. Hull
Keyword(s):  
Volcanic Ash ◽  
Surface Displacement ◽  
Normal Fault ◽  
Historical Earthquakes ◽  
Normal Faults ◽  
Single Event ◽  
Ground Shaking ◽  
Large Earthquakes ◽  
Fault Length ◽  
Strong Ground

Several active normal faults in the onshore and offshore regions of Taranaki are capable of generating large earthquakes and associated strong ground shaking. Historical earthquakes are concentrated offshore of Cape Egmont, and no significant earthquakes have been detected along the major onshore surface faults. The northeaststriking Inglewood fault is a major onshore, southward-dipping normal fault. It has a known length of c. 20 km and an average scarp height of c. 3 m on landforms less than about 15,000 yrs old. Three subsurface excavations at two sites along the Inglewood fault about 15 km from New Plymouth have revealed three surface fault displacements during the last c. 13,000 years. Earthquakes resulting in about 1.2 m of surface displacement occurred at c. 3,500 radiocarbon yrs BP; between 4,000 and 9,000 radiocarbon yrs BP; and between 10,000 and 13,000 radiocarbon yrs BP, judged by the amount of vertical offset of dated volcanic ash layers. Based on average single-event fault slip values of 1.2-3.0 m and a fault length of 20-30 km, the estimated earthquake magnitudes associated with these past movements range from Mw 6.7 to 7.2.

The Performance of Steel-Frame Buildings with Infill Masonry Walls in the 1906 San Francisco Earthquake

2006 ◽  
Vol 22 (2_suppl) ◽  
pp. 43-67 ◽  
Author(s):  
Ronald O. Hamburger ◽  
John D. Meyer
Keyword(s):  
San Francisco ◽  
Steel Frames ◽  
Steel Frame ◽  
Earthquake Damage ◽  
Superior Performance ◽  
Masonry Walls ◽  
Ground Shaking ◽  
Frame Buildings ◽  
Steel Frame Buildings ◽  
Infill Masonry

Following the great 1906 San Francisco earthquake and fire, engineers recognized the superior performance of buildings with complete vertical load–carrying steel frames and infill masonry walls. These buildings were noteworthy in their ability to survive both the ground shaking and fire, many remaining in service today. Observation of this superior performance led many California structural engineers to believe that steel frames were the best structural system for resisting earthquake damage, in turn, leading to a proliferation of steel-frame construction in California cities. Not until the 1994 Northridge earthquake did many California engineers recognize that steel-frame structures can and do experience severe earthquake damage. The performance capability of early steel-frame buildings with infill masonry walls, however, remains unclear, despite improved understanding of their structural response characteristics.

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