Charles-Darwin Annan

Seismic Vulnerability Assessment of Modular Steel Buildings

Contemporary seismic design is based on dissipating earthquake energy through significant inelastic deformations. This study aims at developing an understanding of the inelastic behavior of braced frames of modular steel buildings (MSBs) and assessing their seismic demands and capacities. Incremental dynamic analysis is performed on typical MSB frames. The analysis accounts for their unique detailing requirements. Maximum inter-story drift and peak global roof drift were adopted as critical response parameters. The study revealed significant global seismic capacity and a satisfactory performance at design intensity levels. High concentration of inelasticity due to limited redistribution of internal forces was observed.

Seismic Overstrength in Braced Frames of Modular Steel Buildings

The seismic behavior factor, R, is a critical parameter in contemporary seismic design. In the 2005 edition of the National Building Code of Canada, the R factor consists of ductility related force modification factor, Rd, and overstrength-related force modification factor, Ro. The choice of these factors for design depends on the structural system type. In this investigation, typical braced frames of Modular Steel Buildings (MSBs) are designed and modeled. Nonlinear static pushover analyses are conducted to study the inelastic behavior of these frames. Structural overstrength resulting from redistribution of internal forces in the inelastic range, design assumptions, and strain hardening behavior of steel and displacement ductility are evaluated and their relationships with some key response parameters are assessed. The results show that the reserve strength of MSB-braced systems is greater than that prescribed by the Canadian code for regular braced systems. It also appears that R depends on building height, contrary to what has been prescribed in many seismic design codes. It is concluded that some unique detailing requirements of MSBs need to be considered during design to eliminate undesirable seismic response.

Effect of Directly Welded Stringer-To-Beam Connections on the Analysis and Design of Modular Steel Building Floors

Modular Steel Buildings (MSBs) are fast evolving as an effective alternative to conventional on-site steel construction. An explanation of the concept of modular steel design, including its unique detailing requirements is given in this paper. The paper also focuses on a typical MSB floor system which is achieved by welding the webs of the stringers directly to the floor beams. A typical modular floor grid structure is designed using conventional methods. The floor is then modelled using the finite element method and analyzed under the effect of dead and live service loads. This allows an assessment of the effect of direct welding between stringers and floor beams on the analysis and design of floor beams, stringers, and welded connections. The results reveal that consideration of the true behaviour of direct welding leads to a distribution of forces and moments which is different from those found in conventional steel buildings. A simplified analytical model is proposed to capture such behaviour. Regression functions have been developed to describe the model. In practice, the proposed model can predict the actual forces and moments, leading to a reliable design of modular steel floors.

Constitutive Modeling of Gravelly Soil–Structure Interface Considering Particle Breakage

AbstractThe mechanical behavior of the interface between gravelly soils and structures may play a significant role on the response of many soil-structure systems to loading. Under cyclic excursion ...

Winning Trophies or Making Good Structural Engineers

ing and Indexing: This publication is abstracted in Web of ScienceSM; Science Citation Index Expanded (SciSearch); Journal Citation Reports/Science Edition; Current

Relevance of Traditional Steel Design and Fabrication Requirements to Structural Stainless Steels

Stainless steel is increasingly used in a number of structural applications and less considered an exotic solution to structural engineering problems. A paradigm shift towards life-cycle costing and sustainable development, as well as superior mechanical, thermal and physical characteristics are often cited as the dominant driving force. While significant progress has been made around the world, particularly over the last two decades, in structural stainless steel research, design methods are largely based on those of the well-known carbon steels. Although there is increased understanding of the materials unique mechanical behaviour and structural characteristics, on-going research efforts seek to fully maximise the desirable properties of the material to improve on structural design and performance. It is also expected to facilitate its wider structural applications, making it a structural material of choice. This paper addresses a broad range of fundamental issues affecting material behaviour, design requirements, fabrication, erection and research development of stainless steels in structural applications, and brings together a number of useful leads for both researchers and practitioners. It also assesses the relevance of design and fabrication procedures customary to carbon steels.