Controlled Rocking CLT Walls for Buildings in Regions of Moderate Seismicity: Design Procedure and Numerical Collapse Assessment

Controlled rocking heavy timber walls are designed to rock on their foundations in response to earthquakes. For regions of moderate seismicity, it is proposed that this rocking behaviour can be adequately controlled using only post-tensioning, even with a large force-reduction factor and no supplemental energy dissipation. This article presents a force-based design procedure for controlled rocking cross-laminated timber walls without supplemental energy dissipation, including a method for estimating higher mode effects. Fragility analyses of three prototype walls demonstrate that the procedure can limit the probability of collapse to <10% during a maximum considered earthquake in a region of moderate seismicity.     

Documenting Archaeological Mortuary Features using High Dynamic Range (HDR) Imaging

This technical note presents a refined technique for photo‐documenting archaeological mortuary features using High Dynamic Range (HDR) imaging. Mortuary features in archaeological context can be complex and delicate given the wide variability in grave constructions and preservation of human skeletal remains. It is therefore critical to obtain the greatest detail possible when photo‐documenting these features. HDR techniques represent more contrast in photographs and provide greater detail across the DR of illumination within mortuary features—where complex arrangements of human remains can obscure or darken other elements or associated funerary objects, making them difficult to identify in traditional photographs. HDR can be employed with most standard digital single lens reflex cameras used for archaeological field projects, is easy to learn and employ (as described here), can be processed and produced with commonly used photo editing programs, and is ideal for use in unpredictable conditions that are often encountered with archaeological mortuary features and in field conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Real-Time Dynamic Hybrid Testing Coupling Finite Element and Shaking Table

In this article, a Simulink simulation block with the finite element function is developed on the basis of S-function and implemented as the numerical substructure of real-time dynamic hybrid testing. Thereby, a real-time dynamic hybrid testing system coupling finite element calculation and shaking table testing is achieved. Using the developed system, a shear frame mounted on the soil foundation is tested, in which the shear frame is simulated as the physical model and the foundation is simulated as the finite element model with 132 degrees of freedom. Several cases of the dynamic behavior of soil-structure interaction are studied.     

Identification of Suitable Limit States from Nonlinear Dynamic Analyses of Masonry Structures

Performance-based earthquake engineering, developed over the last decades for the design and assessment of other structures, can also be applied for masonry structures if the particularities of masonry are incorporated into the procedure. According to this methodology, structural performance can be assessed according to damage states which are identified through displacement/damage indicators. While various methods for the identification of limit states from the results of nonlinear static analyses exist, the identification of damage states from the results of nonlinear dynamic analyses is still uncertain. This article investigates a number of criteria allowing to identify the attainment of significant limit states from the results of time history analyses, in terms of appropriately identified response quantities. These criteria are applied to five building prototypes and their results are compared. A comparison with the limit states derived from nonlinear static analyses is also made.     

Effects of Different Record Selection Methods on the Transverse Seismic Response of a Bridge in South Western British Columbia

The seismic response of a continuous 4-span bridge designed according to the current Canadian seismic provisions is investigated using Incremental Dynamic Analysis (IDA). Different earthquake types, including shallow crustal events, interface Cascadia subduction, and deep inslab subduction are considered. The median collapse capacities calculated using different record selection methods including Conditional Mean Spectrum (CMS)-based, Uniform Hazard Spectrum (UHS)-based, and epsilon-based methods are compared. The use of the epsilon-based method generally resulted in the highest collapse capacity predictions, but the CMS-based method was less sensitive to the number of records considered in the IDA.     

动态环境中的企业战略柔性

随着技术创新的加速和经济全球化的日益扩展,变化已成为企业外部环境的基本特征,战略柔性的重要性日益凸显。本文详细分析了动态环境的涵义,探讨了动态环境中战略柔性的理论内涵,并提出了在动态环境下企业增强战略柔性的基本途径。     

An Explicit Integration Scheme for Solving Dynamic Problems of Solid and Porous Media

In this article, an explicit integration scheme for dynamic finite element analysis is developed and the formulations for linear elastic solid and two-phase porous media are derived. The accuracy and stability characteristics analyses show this scheme is second-order accurate, which is the same as the Central Difference Method (CDM), and possesses a broader scope of stability within the range of normal damping ratios of media. Comparing with the CDM, this explicit scheme requires no matrix factorization even if a non diagonal damping matrix is included. Therefore, the dynamic finite element equations can be integrated economically provided that the mass matrix is diagonal. To demonstrate the validity of the present scheme, three examples are provided. First, taking a single-degree-of-freedom system as an example, the results obtained by the proposed scheme are compared with the exact solutions. Second, the dynamic responses of half-space saturated porous media, subjected to a concentrated load pulse at the surface, are analyzed. Both examples show that the results obtained by the proposed scheme agree well with the analytical solutions. Finally, the dynamic responses of a plane strain plate due to a load pulse are analyzed, respectively, by the proposed procedure and the commercial code ABAQUS (both implicit module and explicit module), and the CPU costs are compared.     

Seismic Demand on Shear Panel Dampers Installed in Steel-Framed Bridge Pier Structures

This study is aimed at investigating the demand on shear panel dampers (SPDs) installed in steel structures under strong earthquake motions to serve as guidance for the recommended capacity of SPDs in seismic design. For this purpose, an extensive dynamic analysis is carried out on steel bridge pier structures with SPD devices. To describe the restoring force characteristics of SPDs, the analysis uses a newly developed combined hardening model based on experimental data. The seismic demands made on SPD devices are examined and then summarized to give recommended values for determining the necessary deformation capacity of SPDs.     

Dynamic Stability and Design of C-Bent Columns

Symmetrically reinforced bridge columns with a horizontal cantilever in one direction, called C-bent columns, tend to deform predominantly in the direction of applied moment when subject to strong earthquake shaking. For this reason, the strength in the direction of applied moment is generally increased in design. This article describes the use of inelastic dynamic time history analyses with a suite of ground motion records to quantify the amount of strength increase required to minimize likely peak and permanent displacement demands. It is shown that the strength should be increased by approximately 2.3 times the applied moment in design.