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Mehmet Çelebi

Publications and source records attributed to Mehmet Çelebi.

At least 37 records · Page 2Linked to original sources
USGS2004

Seismic response analysis of a 13-story steel moment-framed building in Alhambra, California

The seismic performance of steel moment-framed buildings has been of particular interest since brittle fractures were discovered at the beam-column connections of some frames following the M6.7 1994 Northridge earthquake. This report presents an investigation of the seismic behavior of an instrumented 13-story steel moment frame building located in the greater Los Angeles area of California. An extensive strong motion dataset, ambient vibration data, engineering drawings and earthquake damage reports are available for this building. The data are described and subsequently analyzed. The results of the analyses show that the building response is more complex than would be expected from its highly symmetrical geometry. The building's response is characterized by low damping in the fundamental mode, larger peak accelerations in the intermediate stories than at the roof, extended periods of vibration after the cessation of strong input shaking, beating in the response, and significant torsion during strong shaking at the top of the concrete piers which extend from the basement to the second floor. The analyses of the data and all damage detection methods employed except one method based on system identification indicate that the response of the structure was elastic in all recorded earthquakes. These findings are in general agreement with the results of intrusive inspections (meaning fireproofing and architectural finishes were removed) conducted on approximately 5 percent of the moment connections following the Northridge earthquake, which found no earthquake damage.

Open-File Report↗
USGS2000

Seismic instrumentation of buildings

The purpose of this report is to provide information on how and why we deploy seismic instruments in and around building structures. The recorded response data from buildings and other instrumented structures can be and are being primarily used to facilitate necessary studies to improve building codes and therefore reduce losses of life and property during damaging earthquakes. Other uses of such data can be in emergency response situations in large urban environments. The report discusses typical instrumentation schemes, existing instrumentation programs, the steps generally followed in instrumenting a structure, selection and type of instruments, installation and maintenance requirements and data retrieval and processing issues. In addition, a summary section on how recorded response data have been utilized is included. The benefits from instrumentation of structural systems are discussed.

Open-File Report↗
USGS1995

Saving lives through better design standards

Over the past 30 years, scientists have put together a more complete picture of how the ground shakes during earthquakes. They have learned that shaking near the source of earthquakes is far more severe than once thought and that soft ground shakes more strongly than hard rock.This knowledge has enabled engineers to improve design standards so that structures arebetter able to survive strong earthquakes. When the 1989 Loma Prieta earthquake struck, 42 people tragically lost their lives in the collapse of a half-mile-long section of the Cypress structure, an elevated double-decker freeway in Oakland, California.Yet adjacent parts of this structure withstood the magnitude 6.9 temblor—why? The part that collapsed was built on man-made fill over soft mud, whereas adjacent sections stood on older, firmer sand and gravel deposits. Following the collapse, scientists set out instruments in the area to record the earthquake's many strong aftershocks. These instruments showed that the softer ground shook more forcefully than the firmer material-even twice as violently

California↗
USGS1993

Seismic response of eccentrically braced tall buildings

Spectral analysis and system identification techniques are used to analyze a set of acceleration reponse records obtained during the Loma Prieta earthquake from the 47-story, moment-resisting framed and eccentrically braced Embarcadero Building (EMB). The EMB was constructed in 1979 based on the 1976 Uniform Building Code requirements and a design response spectra defined by two levels of earthquake performances. The EMB is in the lower market area of San Francisco, which is of great interest to the engineering community because of the area's soft soil characteristics that amplify ground motions originating at long distances, and because the Embarcadero freeway suffered extensive damage during the earthquake and was razed in 1991. The first modal frequencies of the building at approximately 0.19 Hz (north-south) and 0.16 Hz (east-west) are identified. The torsional response and rocking motions of the building are insignificant. Discontinuity of stiffness and mass at the 40th floor level causes significant response issues above that floor such as excessive drift ratios.

Journal of Structural Engineering↗
USGS1993

Seismic responses of two adjacent buildings. I. Data and analyses

In this two-part paper, responses of two, adjacent, seven-story buildings in Norwalk, California, to the Whittier-Narrows, Calif, earthquake of Oct. 1, 1987 are studied. Building A, instrumented according to code recommendations, and building B, extensively instrumented, are offset by 16.3 m from one another. The data set includes motions from the superstructure of both buildings, from a downhole below the foundation of building B, and from three free-field sites. Part I of the paper includes descriptions of the buildings, site, instrumentation, and analysis of the data of each building. System identification and spectral analysis techniques are employed in part I. Building A has identical first-mode frequencies of 0.65 Hz for both building axes. The strong-motion response characteristics of building A are considerably different than those determined from low-amplitude tests. Building B has fundamental modes at 0.76 Hz and 0.83 Hz in the major and minor axes, respectively. Torsional and diaphragm effects in building B are negligible.

Journal of Structural Engineering↗
USGS1992

Highlights of the 13 March 1992 Erzincan (Turkey) earthquake

The March 13, 1992 Ms = 6.8 Erzincan earthquake in Turkey is highlighted here. The epicenter of this earthquake was located 7.7 km from the eastern end of the North Anatolian fault. The strong motions recorded in Erzincan had peak ground accelerations of approximately 0.5 g, accompanied by a pulse of 2 seconds. The duration of the earthquake was 7 seconds. This earthquake caused collapse of about 150 buildings--mainly to 4-5-story reinforced, concrete-framed buildings with infill walls. This damage, which is discussed, can be attributed to non-compliance with seismic codes.

Conference Paper↗
USGS1990

Method to estimate center of rigidity using vibration recordings

A method to estimate the center of rigidity of buildings by using vibration recordings is presented. The method is based on the criterion that the coherence of translational motions with the rotational motion is minimum at the center of rigidity. Since the coherence is a function of frequency, a gross but frequency-independent measure of the coherency is defined as the integral of the coherence function over the frequency. The center of rigidity is determined by minimizing this integral. The formulation is given for two-dimensional motions. Two examples are presented for the method; a rectangular building with ambient-vibration recordings, and a triangular building with earthquake-vibration recordings. Although the examples given are for buildings, the method can be applied to any structure with two-dimensional motions.

Journal of Structural Engineering↗
USGS1989

Seismic response of a large-span roof diaphragm

Records obtained from the West Valley College Gymnasium in Saratoga, California during the 1984 Morgan Hill earthquake are used to study the dynamic behavior of the overall gymnasium as well as its flexible disaphragm. The ground-level motions recorded in the two orthogonal axes of the structure differ considerably in peak acceleration and amplify by approximately 1.5 times at the roof edges and by 4-5 times at the center of the diaphragm. The diaphragm responds with a frequency of approximately 4 Hz in both orthogonal axes. A simple finite-element model is used to match the fundamental frequency of the diaphragm with that from the records. Using this model and the ground-level motions as input, the diaphragm center displacements are calculated by varying the structural damping. Best comparisons are obtained for 5% damping. These results are discussed in terms of the code provisions.

Earthquake Spectra↗