Response Spectrum Curve Research Articles

On the Application of the Critical Excitation Method to Aseismic Design

ABSTRACT The problem of critical excitation of linear structures subjected to earthquake support motion is investigated. For a given time duration and peak ground acceleration, the critical time history which maximizes the absolute acceleration response is obtained. Similar considerations are given to the critical ground acceleration which maximizes the relative displacement and velocity responses. Some bounds on the response spectra curves are obtained and discussed.

Seismic Design Criteria for Hydroelectric Plant

On the basis of the latest study and research in the field of seismology and earthquake resistant design, new criteria are used to design and construct a safer power plant. Devil Canyon Power Plant is located in the immediate vicinity of two major faults in California, i.e., the San Andreas Fault and the Santa Ana Fault. Earthquake acceleration response spectrum curves are used to define more accurately loads exerted on the structure during a major earthquake. Also, special design considerations are enumerated.

Structural response results during July 29, 1970 earthquake in Burma-India border region

Abstract The data from the Structural Response Recorder installations during the July 29, 1970 earthquake in the Burma-India border region have been interpreted in terms of structural response results. These results suggest the possibility of dependence of the nature of the response spectrum curves on the azimuth of recording. The strike of the fault plane, determined on the basis of the directions of the maximum recorded amplitudes, coincides with the local structural trend and is in conformity with the fault-plane solutions for some previous earthquakes in the region.

Long distance effects of the 28 march 1970 gediz turkey earthquake

AbstractIn this paper, soil‐structure interaction studies are presented for buildings which collapsed at the Tofas automobile factory, Bursa, Turkey, during the 28 March 1970 Gediz earthquake. Acceleration response spectrum curves of the ground were determined using the vibrations of an after shock recorded by a Willmore velocity seismometer. These spectrum curves provide an essential source of information for establishing the reasons of collapse, as well as for explaining the relative response to the earthquake of various buildings in the factory area.The factory not only is 135 km away from the epicentre, but also is far outside the fifth degree damage intensity zone. The prime reason why a low value of ground acceleration caused such surprisingly heavy damage to modern reinforced concrete structures is concluded to be the resonance phenomenon arising from the natural period of the structures coinciding with the predominant period of the soil.

Analysis of the Pacoima dam accelerogram—San Fernando, California, earthquake of 1971

Integrated ground velocities and displacements calculated from the accelerogram recorded at the Pacoima dam site indicate that the strong ground motion was predominately in the vertical and NS direction, in general agreement with the mechanism of faulting as inferred from aftershock studies, and with fault displacements observed in the field. High-frequency peak accelerations of 1.25 g were recorded in two horizontal directions, these being the highest ground accelerations so far recorded for earthquakes. Response spectrum curves calculated from the accelerograms do not show unusual features, and the numerical values are consistent with past experience. The high-frequency, high-amplitude impulsive ground motion associated with the highest peak accelerations did not contribute significantly to the over-all response spectrum values. The presence of the high-frequency motions in the recorded accelerograms is presumably the consequence of the proximity of the recording site to the fault dislocation.

Seismic analysis of piping systems

Seismic analysis of piping systems has been reviewed based on the single degree response spectrum curve technique and lumped mass parameters. Using the design of the primary coolant loop of a typical nuclear power plant as an example, both stiffness and flexibility formulations have been discussed in detail, in which the pipes, valves, steam generator, and coolant pump are included in the three dimensional model. Since it is a general practice to choose only part of the six degrees-of-freedom in each concentrated mass, the flexibility matrix constructed based on this reduced system is not complete. Consequently, the usual approach of obtaining shear forces from a stiffness matrix may be in error when the latter has to be computed by inverting the reduced flexibility matrix. This difficulty can be overcome by reducing the stiffness matrix after inverting the complete flexibility matrix. However, this is not always practical because the size of the matrix, which has to be inverted, may be large. On the other hand, whether the use of stiffness matrix together with the maximum relative displacement vector will give a maximum reverse effective force vector is uncertain. Consequently, the stiffness method may not always yield satisfactory results. In the light of these difficulties, to compute an approximate but conservative absolute acceleration vector becomes more attractive in the sense that this process does not require inverting any matrix. The reverse effective force vector obtained by multiplying the diagonal mass matrix with the maximum absolute acceleration vector will, indeed, be a maximum.

An analysis of seismoscope data from the Parkfield earthquake of June 27, 1966

AbstractAn analysis of 16 seismoscope records from the Parkfield earthquake indicates the general usefulness of seismoscope data as a supplement to information produced by recording accelerographs. The pattern of attenuation of response spectrum values with distance from the fault was obtained, and certain anomalies in response spectrum values which may be related to local geologic structure were noted. The initial strong ground motions in the immediate vicinity of the fault were found to be predominately transverse to the fault. A direct comparison of seismoscope results with response spectrum curves calculated from recorded groud acceleration-time curves indicates an overall seismoscope accuracy under typical field conditions of 10-15 per cent.

Mode superposition in multi-degree of freedom systems using earthquake response spectrum data

ABSTRACT Dynamic responses of a series of typical three-degree of freedom structures to strong-motion earthquake excitation were calculated by analog computer techniques and were compared with approximate responses obtained by a superposition of individual modes derived from response spectrum curves. The results indicate that a suitably weighted average of the sum of the absolute values of the individual modes and the square root of the sum of the squares of the modes will give a practical design criterion for the base shear forces in multi-story buildings. For critical designs, this weighted average reduces to the absolute sum of the modes, which is found to be close to the true value for a significantly high proportion of typical earthquake-structure combinations.

A simplified instrument for recording strong motion earthquakes

Abstract A strong-motion earthquake recorder for the direct measurement of one point on the response spectrum curve is described, and results obtained with the instrument under field conditions are compared with those obtained by a standard spectrum analysis of accelerograph records. The device has the advantages of low initial cost and of low maintenance expense, and can thus be installed in relatively large numbers. A network of such instruments located at points having various local geological conditions is proposed as a supplement to the U. S. Coast and Geodetic Survey strong-motion seismograph system.

Ground accelerations caused by large quarry blasts

Abstract Ground acceleration-time measurements have been made within 2000 ft. of two quarry blasts of total charge weight 185 tons and 673 tons. Ground accelerations were of a character and magnitude similar to those associated with damaging earthquakes. Complete response spectrum curves calculated from the acceleration records are presented. Direct comparisons are made between these results and previous similar measuements and calculations using identical instruments, which have been made of strong-motion earthquakes, H. E. blasts, and the Rainier nuclear blast.

Behavior of Structures During Earthquakes

Behavior is described by response spectrum curves which show effect of size and distance of earthquake and period and damping of structure; high elastic stresses are developed during strong ground motion; type of limit design is indicated.

An analysis of strong-motion accelerometer data from the San Francisco earthquake of March 22, 1957

AbstractThe San Francisco earthquake of March 22, 1957, was recorded simultaneously by accelerometers at five United States Coast and Geodetic Survey stations in the San Francisco area. Response spectrum curves were computed from the acceleration-time records, and from these response spectrum curves the spectrum intensities have been determined. From these spectrum intensities certain conclusions are drawn as to: (1) the effects of local geology on the recorded ground motions; (2) the calculation of total energy released by the earthquake from strong-motion accelerometer records; (3) possible influence of structural dynamic behavior on the accelerations recorded in building basements, and the relationship between basement accelerations and ground accelerations; and (4) the applicability of a simplified type of strong-motion earthquake instrument for investigations of local distribution effects. A general comparison is made between the present earthquake and typical Pacific Coast earthquakes.