Civil Engineering Association

P-delta design in seismic regions
MacRae, Gregory A.; Priestley, M. J. N.; Tao, Jian
SSRP-93/05, Dept. of Applied Mechanics and Engineering Sciences, University of California, San Diego, Structural Systems Research Project, 1993-06, PDF (5.4 MB) (500/S778/93/05)

Rational and simple design recommendations concerning the design of structures in seismic regions are made based on the response of single-degree of freedom oscillators and an understanding of dynamic response. The recommendations relate to when the P-delta effect can be ignored, how to conduct design for P-delta when it cannot be ignored, and the effect of P-delta acting along the member length. As a background to these recommendations, a literature summary is provided and the inelastic behavior of oscillators is described.

PDF|RAR 5.59|5.22 MB

---

An Engineering manual for settlement studies
Duncan, James M.; Buchignani, Albert L.
UCB/GT-76-01, University of California, Berkeley, Geotechnical Engineering, 1976-06, PDF (30 MB)

The manual provides a simple, practical guide for settlement studies addressing: settlement problems and building damage due to settlement, methods of estimating settlement of shallow foundations on sand, methods of estimating immediate consolidation and secondary compression settlements of shallow foundations on clay, methods of estimating settlements of pile foundations, and, methods of eliminating, reducing or coping with settlements.

PDF|RAR 30.47|20.68 MB

Earthquake response considerations of broad liquid storage tanks
Cambra, Frank J.
UCB/EERC-82/25, Earthquake Engineering Research Center, University of California, Berkeley, 1982-11, 193 pages (540/C35/1982)

This paper examines the influences of tank geometry and foundation stiffness variation on the simulated seismic structural response of a broad tank model. An empirical method for describing tank bottom plate uplift geometry is proposed which recognizes radial catenary force and foundation stiffness. Axial symmetric lift, static tilt, and dynamic shaking table tests were performed at the Univ. of California, Berkeley, Earthquake Simulator Laboratory. A structural geometric survey of a crude oil storage tank, measuring 63 ft 10 in tall by 289 ft 6 in wide, was conducted to establish a comparative base by which to evaluate the model tank eccentricities. It is concluded that the imperfections of the model tank defined by Fourier coefficients can be as much as an order of magnitude greater than those observed in the field. It is also concluded that foundation flexibility variation will significantly change the seismic response of tanks. Further, it is believed that out-of-round seismic vibration response, thought to be associated with eccentricities in tank fabrication geometry, will be less significant for large operating broad tanks resulting in lower amplitudes of asymmetric and higher order Fourier stress contribution. However, other parameters, such as uplifting, may still excite asymmetric and higher order Fourier response.

PDF 8.34 MB

Development, implementation, and verification of dynamic analysis models for multi-spherical sliding bearings
Fenz, Daniel M.; Constantinou, M. C.
MCEER 08-0018, Buffalo, NY : Multidisciplinary Center for Earthquake Engineering Research, Technical report, 1520-295X ;, 2008, xxiii,279p - PDF (500 N24 08-18)

This report describes the formulation, implementation and validation of multi-spherical sliding bearing models that can be used for response history analysis. When configured to exhibit adaptive behavior, double and triple Friction Pendulum (FP) bearings exhibit hysteretic behavior that is more complex than that exhibited by current seismic isolation devices. The methodologies described in this report are verified by comparing the results obtained from shake-table testing of a quarter-scale, six-story model to those predicted by response history analysis. There is generally good agreement even in cases of extreme response, which attests to the proposed models' robustness and overall validity.

PDF 20.18 MB

Experimental study of 'elephant foot bulge' instability of thin-walled metal tanks

Jia, Zi H.; Ketter, Robert L.

NCEER-89-0004, Buffalo, N.Y. : National Center for Earthquake Engineering, Technical report, 1989, 1v (500 N24 89-04)

This study is primarily intended to identify and quantify the 'elephant foot bulge' failure mechanism. Shaking table studies were carried out to investigate the buckling behavior or cylindrical liquid storage tanks under base excitations. Two specially designed aluminum tank models were fabricated, and they were subjected to various seismic loadings. During the tests, the phenomena of 'elephant foot bulge' were clearly observed for both model tanks. Test results in this study indicate that current seismic design criteria do not necessarily safeguard against this type of failure. New design criteria and design alternatives are needed.

PDF|RAR 2.22|2.01 MB

On problems in the use of earthquake response spectrum methods for fluid-structure-soil interaction

Rammerstorfer, Franz G.; Scharf, Knut; Fischer, Franz D.

PVP - Vol. 157, American Society of Mechanical Engineers, New York, Sloshing and Fluid Structure Vibration -- 1989, presented at The 1989 ASME Pressure Vessels and Piping Conference, Honolulu, Hawaii, July 23-27, 1989, 1989, pdf (540/A75/1989/v.157)

The response spectrum method is well established in linear structural mechanics for estimating the maximum stresses or displacements in structures during an earthquake, characterized by the response spectra. These problems require the relative displacement spectra only. However, in order to estimate the maximum dynamically activated pressure distribution in fluid-structure interaction problems using the response spectrum method acceleration spectra are employed. With respect to a proper superposition of the individual contributions to the dynamically activated maximum pressure response, the absolute as well as relative accelerations become important. Furthermore, a suitable superposition rule must be chosen. A further problem discussed is the simultaneous horizontal (N-S and E-W) and vertical excitation of a liquid-filled storage tank. Results show that SRSS superposition is not suitable for estimating the maximum pressure or the most dangerous situations with respect to stability of the structure. Principally, from the theoretical point of view, the response spectrum method must not be used if nonlinearities are involved. A proposal for an engineering approach using the response spectrum method even for uplifting tanks is discussed. This proposal accounts for the amplitude dependence of the natural frequencies of the interaction vibrations.

PDF 1.03 MB | RAR 0.89 MB

A study of seismically resistant eccentrically braced steel frame systems

Kasai, Kazuhiko; Popov, Egor P.

UCB/EERC-86/01, Earthquake Engineering Research Center, University of California, Berkeley, 1986-01, 309 pages (530/K245/1986)

Basic plastic theory for an eccentrically braced frame (EBF) force field and an ideal rigid-plastic displacement field are explained in the first part of this report. Based on these, a simple method for obtaining the lateral load-carrying plastic capacity of an EBF is proposed. Further, the proposed plastic theory is employed for various plastic problems of EBFs, where the accuracy of the theory is demonstrated by comparing results found using the theory with elastoplastic finite element analysis results. The second part of this report includes the effect of link inelastic deformation on both link and EBF behavior. Strain-hardening and various failures of the link are discussed. First, the experimental program for a subassemblage simulating EBF action is described. The observed cyclic behavior of different length links tested with or without simultaneously acting axial forces is reported. Next, the experimental results are analyzed with emphasis on the influence of the link length on the performance. Moment, shear, and axial force interaction, as well as the effect of strain-hardening on moment redistribution, energy dissipation, and flange and web buckling, are considered. Based on these results, the ultimate state design for cyclically loaded links is proposed. Further, a simple new criterion for web stiffener spacing to prevent premature cyclic web buckling is proposed using the secant modulus method based on experimental data for 30 links. The application of this criterion to an EBF ultimate state design is also discussed.


PDF 10.18 MB | RAR 8.83 MB

---

Design of links and beam-to-column connections for eccentrically braced steel frames

Popov, Egor P.; Malley, James O.

UCB/EERC-83/03, Earthquake Engineering Research Center, University of California, Berkeley, 1983-01, 67 pages (530/P65/1983D)

This report has been prepared to be Chapter 11 of the upcoming "ASCE Manual on Beam-to-Column Building Connections," under review by members of the Monograph Task Committee of the Committee on Structural Connections of the ASCE Structural Div. The chapter first introduces the concept and points out some of the advantages of eccentrically braced frames (EBFs) for seismically resistant steel construction. A brief exposition of some of the available design procedures for such frames is provided. An approach is given for appraising the performance of the active links, i.e., beam segments between braces and/or columns, for achieving a stiff elastic structure together with an indication of the ductility demands placed on the links at extreme cyclic overloads. Suggestions for link length selection are made based on experimental results with some 28 full-sized isolated links. Some of the obtained results in these experiments are described and selected hysteretic loops for cyclic loadings are given. Illustrated in this chapter are suggested details for the following items: link-column connections, link-brace connections, and spacing and sizing of link-web stiffeners. Possible applications of EBFs in nonseismic design are also pointed out.

PDF 2.90 MB | RAR 2.34 MB

Design considerations for shear links in eccentrically braced frames

Malley, James O.; Popov, Egor P.
UCB/EERC-83/24, Earthquake Engineering Research Center, University of California, Berkeley, 1983-11, 126 pages (530/M224/1983)

This study addresses three aspects of shear link behavior critical to the economical design of an eccentrically braced frame which employs shear links: the sensitivity of link behavior to the imposed loading history, the link-column connection detail, and the web stiffener design and details. Results for twelve full-size shear link specimens are presented. Each of the specimens was designed to investigate specific shear link response characteristics. Four specimens were tested with stiffener details which differed significantly from those of previous experiments and early design applications. Another set of four specimens were designed and tested with widely varying loading histories. A set of four specimens which employed conventional moment resisting connection details were also tested. The qualitative and quantitative results of these experiments are compared and analyzed using energy dissipation capacity as a major parameter. Test conclusions and design recommendations are presented. A practical method for web stiffener design is developed which considers both the axial force and bending rigidity requirements which shear link web stiffeners must satisfy. An example of the method is given in an appendix. A design procedure for eccentrically braced frames which employ shear links is outlined, based on the major considerations of shear link design. This procedure includes recommendations on the determination of structural configuration, member sizes, link-connection details, and web stiffener sizes and details. The suggested connection and stiffener details are illustrated.

PDF 7.89 MB | RAR 6.59 MB

---

Structural steel bracing systems: behavior under cyclic loading

Popov, Egor P.; Takanashi, Koichi; Roeder, Charles W.
UCB/EERC-76/17, Earthquake Engineering Research Center, University of California, Berkeley, 1976-06, 81 pages (515/P65/1976)

A survey is made of existing literature on the performance of steel braced frame structures under cyclic excitations. Particular emphasis is placed on inelastic behavior under extreme credible excitations which may occur during a severe earthquake. The experimental and analytical studies of the behavior of an individual brace are described. The effect of the individual braces on the behavior of the entire structural system is then brought out. The behavior of a concentrically braced frame is discussed with respect to dynamic response to given excitations as well as its quasistatic hysteretic behavior under cyclic load. The advantages and limitations of the two possible approaches to design and correlations are indicated. The overall problem is very complex and has not been completely resolved, but a number of plausible design concepts have been advanced. These are reviewed in the report. Most of these are based on static methods of analysis and are intended to assure good dynamic performance of the structure. These approaches are not a substitute for dynamic analysis, but they help simplify the design procedure. Several design concepts, such as the eccentrically connected braced frame, show that braced frames can perform well under extreme excitations. Finally, the limitations of current knowledge are summarized and recommendations for further research are made.

PDF 5.69 MB | RAR 4.33 MB

Inelastic buckling of steel struts under cyclic load reversals

Black, R. Gary; Wenger, W. A.; Popov, Egor P.
UCB/EERC-80/40, Earthquake Engineering Research Center, University of California, Berkeley, 1980-10, 174 pages (530/B538/1980)

Cyclic axial loading experiments simulating severe seismic conditions are described for 24 structural steel struts of sizes and shapes typically employed as braces in small to moderately large steel buildings. The cross-sectional geometries of the specimens were also chosen to model the larger, heavier struts. Six of the 24 members were pinned at one end and fixed at the other, while the remaining 18 were pinned at both ends. The range of cross-sectional shapes included wide flanges, double-angles, double-channels, structural tees, thin- and thick-walled pipes, and thin- and thick-walled square tubes. The responses of the specimens are evaluated and special attention paid to the effects of cross-sectional shape, end conditions, and slenderness ratio using hysteretic envelopes. While investigating the major parameters that influence a member's performance under cyclic loading, some important properties were recognized and quantified. Reduction factors were developed, which can account for the Bauschinger effect and initial curvature of struts. These factors can be used with an American Iron and Steel Inst. code-determined load to estimate the deteriorating compressive capacity of a strut during a few consecutive cycles of full inelastic load reversals. Some design recommendations are made for builtup members likely to experience severe load reversals.

PDF 45.02 MB | RAR 36.39 MB

Seismic moment connections for moment-resisting steel frames

Popov, Egor P.
UCB/EERC-83/02, Earthquake Engineering Research Center, University of California, Berkeley, 1983-01, 61 pages (530/P65/1983S)

This report has been prepared to be Chapter 6 of the forthcoming "ASCE Manual on Beam-to-Column Building Connections," under review by members of the Monograph Task Committee of the Committee on Structural Connections of the ASCE Structural Div. The chapter provides an overview of the state of the art for the design of steel moment connections for high seismic risk regions. The need to design such connections to remain ductile when subjected to full-load reversals is indicated first. The generally accepted approach of "strong columns-weak girders," i.e., designing the joints to develop inelastic activity in the connections and beams rather than in the columns, is adhered to throughout. A major section is devoted to presentation of experimental results to illustrate the observed behavior of beam-to-column connections and column panel zones under severe cyclic loadings simulating extreme seismic conditions. Procedures are given for seismic moment joint calculations pertaining to flange beam connections, web connections, and panel zone design. Typical seismic moment connections of beam-to-column flanges as well as to webs and column splices are illustrated. The chapter concludes by identifying those problems requiring further research.

PDF 7.93 MB | RAR 7.42 MB

Seismic resistant design of base isolated multistorey structures

Andriono, Takim

90-12, Dept. of Civil Engineering, University of Canterbury, Christchurch, New Zealand, 1990-05, PDF (16 MB) (620/A52/1990)

The effects of various structural parameters and ground motion characteristics on the seismic response of base-isolated multistory structures are investigated. Results are used to develop two simplified analysis methods for practical design. The first method, which is called the code-type approach, can be used to accurately estimate the inertia forces, not only at the level of the isolation devices, but throughout the height of the multistory structure. It is recommended for use as a preliminary design tool or even a final design tool for simple base-isolated multistory structures. The second procedure, which is based on the component mode synthesis method, is suggested for final design purposes of more complex base-isolated multistory structures. This method enables the designer to evaluate the effects of the isolation devices on the contribution of each mode of vibration to the total response of the structure.

PDF 16.49 MB | RAR 15.83 MB