Minimum Design Loads for Buildings and Other Structures provides requirements for general structural design and includes means for determining dead, live, soil, flood, wind, snow, rain, atmospheric ice, and earthquake loads, as well as their combinations, which are suitable for inclusion in building codes and other documents. This Standard, a revision of ASCE/SEI 7-05, offers a complete update and reorganization of the wind load provisions, expanding them from one chapter into six. The Standard contains new ultimate event wind maps with corresponding reductions in load factors, so that the loads are not affected, and updates the seismic loads with new risk-targeted seismic maps. The snow, live, and atmospheric icing provisions are updated as well. In addition, the Standard includes a detailed Commentary with explanatory and supplementary information designed to assist building code committees and regulatory authorities. Standard ASCE/SEI 7 is an integral part of building codes in the United States. Many of the load provisions are substantially adopted by reference in the International Building Code and the NFPA 5000 Building Construction and Safety Code. Structural engineers, architects, and those engaged in preparing and administering local building codes will find this Standard an essential reference in their practice. Note: New orders are fulfilled from the second printing, which incorporates the errata to the first printing.

Minimum Design Loads for Buildings and Other Structures

Analysis of machine foundation vibrations: State of the art

The driven monopile is currently the preferred foundation type for most offshore wind farms. While the static capacity of the monopile is important, a safe design must also address issues of accumulated rotation and changes in stiffness after long-term cyclic loading. Design guidance on this issue is limited. To address this, a series of laboratory tests were conducted where a stiff pile in drained sand was subjected to between 8000 and 60 000 cycles of combined moment and horizontal loading. A typical design for an offshore wind turbine monopile was used as a basis for the study, to ensure that pile dimensions and loading ranges were realistic. A complete non-dimensional framework for stiff piles in sand is presented, and applied to interpret the test results. The accumulated rotation was found to be dependent on relative density, and was strongly affected by the characteristics of the applied cyclic load. Particular loading characteristics were found to cause a significant increase in the accumulated ro...

https://www.icevirtuallibrary.com/doi/pdf/10.1680/geot.7.00196

Response of stiff piles in sand to long-term cyclic lateral loading

Methode d'obtention de la reponse dynamique d'une fondation rigide etendue sur un demi-espace elastique lorsqu'elle est soumise a un mouvement du sol variant spatialement incluant a la fois des effets deterministes et aleatoires. Description des resultats numeriques pour une fondation carree rigide et pour un mouvement du sol caracterise par une fonction de coherence spatiale particuliere. Les resultats obtenus indiquent que le mouvement du sol spatialement aleatoire produit des effets similaires aux effets deterministes du passage d'une onde incluant la reduction des composantes de translation de la reponse aux hautes frequences et la creation d'un balancement

Response of a rigid foundation to a spatially random ground motion

An inexpensive and realistic procedure is developed for estimating the lateral dynamic stiffness and damping of flexible piles embedded in arbitrarily layered soil deposits. Starting point is the determination of the pile deflection profile for a static force at the top using any reasonable method—beam‐on‐Winkler foundation, finite elements, well‐instrumented pile load tests in the field, etc. Material as well as radiation damping due to waves emanating at different depths from the pile‐soil interface are rationally taken into account; the overall equivalent damping at the top of the pile is then obtained as a function of frequency by means of a suitable energy relationship. The method is applied to study the dynamic behavior of three different piles embedded in two idealized and one actual layered soil deposit; the results of the method, obtained by hand computations, compare favorably with the results of three dimensional dynamic finite element analyses.

Horizontal Response of Piles in Layered Soils

Factors influencing the behavior of buried pipelines subjected to earthquake faulting

Simple expressions are developed for the equivalent horizontal spring and damping coefficients at the top of an end-bearing pile embedded in a uniform linear soil. Beam on elastic foundation (BEF) and dynamic finite element analyses are used for this purpose. It is demonstrated that, for long end-bearing piles, the top displacement response at high frequencies is independent of the pile length, and the pile behaves identically to a long floating pile in a half-space. A numerical criterion is presented to decide when a pile is long or short. All results are expressed as a function of the pile and soil Young’s Moduli, E\dp and E\ds, and they are valid for a range of Poisson’s Ratios of the soil between 0.25 and 0.49. Finally, expressions are also presented for the soil springs and dashpots required for more complicated BEF analyses of piles in multilayer soils. The results presented in the paper show good agreement with previous studies.

Horizontal stiffness and damping of single piles

The study reported herein attempts to characterize the seismic behavior of cylindrical on‐grade, steel liquid storage tanks subject to the ground shaking hazard. The behavior is quantified by fragility curves that resulted from an analysis of the reported performance of over 400 tanks in nine separate earthquake events. The damage states used herein to characterize damage (i.e., slight, moderate, etc.) are intended to mirror damage state descriptions in the HAZUS Earthquake Loss Estimation Methodology. The amount of ground shaking is quantified by the peak ground acceleration (PGA) at the site. The influence of the tank's height to diameter ratio, H/D, as well as the relative amount of stored contents, % Full, are investigated and were found to have had a significant effect upon tank seismic performance. Finally, the fragility curves developed herein are compared to corresponding relations currently available in the technical literature.

Seismic Fragility Curves for On-Grade Steel Tanks:

Permanent ground deformation is a severe hazard for continuous buried pipelines. This technical paper presents results from four centrifuge tests designed to investigate the influence of pipe-fault orientation on pipe behavior under earthquake faulting. The experimental setup and procedures are described, and the test results are presented. The test results show that, as expected, pipe axial strain is strongly influenced by the pipe-fault orientation angle, whereas the influence of pipe-fault orientation angle on pipe bending strain is minor. The measured pipe strains were shown to follow the trend predicted by the Kennedy model. Also, through a parametric study using the Kennedy model, the experimental data were extrapolated for cases of pipeline with longer unanchored length. By combing the data from strain gauges and tactile pressure sensors, transverse force–deformation relations or p–y relations for the pipe were determined. The data indicates that the underlying p–y relationship varies along the len...

Centrifuge Modeling of Earthquake Effects on Buried High-Density Polyethylene (HDPE) Pipelines Crossing Fault Zones

A fragility relation for buried segmented pipe subject to either the wave propagation or permanent ground deformation (PGD) hazard is presented. In the past, relations to estimate wave propagation damage to buried segmented pipe frequently use peak particle velocity (Vmax) to characterize the seismic hazard. For example, in 1993, O’Rourke and Ayala developed an empirical relation between damage (quantified by repairs per kilometer of pipe) and Vmax using data from four U.S. and two Mexican events. Existing fragility relations for PGD typically characterize the hazard by the amount of permanent ground movement. It is shown herein that for statistically reliable data, differences in estimated wave propagation repair rates become much smaller when the seismic shaking is characterized by ground strain as opposed to Vmax. Furthermore, damage rates for PGD are shown to be consistent with those for wave propagation when the PGD hazard is similarly characterized by ground strain. The combined wave propag...

Michael J. O'Rourke

Papers

Factors influencing the behavior of buried pipelines subjected to earthquake faulting

Horizontal stiffness and damping of single piles

Seismic Fragility Curves for On-Grade Steel Tanks:

Centrifuge Modeling of Earthquake Effects on Buried High-Density Polyethylene (HDPE) Pipelines Crossing Fault Zones

Seismic Damage to Segmented Buried Pipe