Seismic Evaluation of Steel Moment Resisting Frames (MRFs)—Supported by Loose Granular Soil

Soil underneath a structure might affect the behavior and the overall response of the structure in seismic events. The role of loose soil conditions and the inclusion of soil-structure interaction (SSI) in the analysis are important issues that need to be addressed. Since steel structures are light, two configurations designed as spatial and perimeter are considered to study the effect of soil on the steel structural frames for the same building. The paper provides a parametric analysis on the influence of SSI on the overall performance of MRFs (Moment Resisting Frames) according to the provisions of Saudi Building Code (SBC) [1]. A case study has been developed in which spatial and perimeter moment resisting frames of 12, 6 and 3 stories residential buildings are designed using Saudi Building Code (SBC) prescriptions. A modal response spectrum analysis has been carried out to see the influence of SSI on the fundamental period of vibration, top story displacement and inter-story drift limitations. Moreover, a static non-linear analysis has been performed to investigate the performance of frames, thus allowing to identify the influence of SSI on the structural design of steel MRFs.

Codal Requirements Using Capacity Design Philosophy, and Their Applications in the Design of Steel Structures in Seismic Zones

The use of steel structures in the developing countries is limited in spite of its better performance in the case of seismic events due to its high ductility. Although steel structures behave well under seismic excitation, nevertheless the use of structural steel is limiting these days. This paper aims to address various parameters related to the capacity design approach involved in the seismic design of conventional steel structures. Few cases of the early steel structures construction such as bridges in Pakistan are briefly described. Philosophies based on the capacity design approach and the importance of conventional steel lateral load resisting systems with their global mechanisms are provided. The design procedures of Eurocode 8 for Steel Moment resisting frames, Concentric cross braced frames and Eccentric braced frames are given and illustrated. It is believed that the paper will contribute and will be helpful for the designers, researchers and academicians involve in the study of lateral load resisting systems for incorporating in the design process. Since synopsis tables are provided, therefore this will allow a clear understanding of the capacity design approach for different lateral load resisting systems.

Performance of Rigid Steel Frames under Adequate Soil Conditions Using Seismic Code Provisions

This study is focused on?nonlinear analysis and design of?spatial and perimeter moment resisting frames for a 9-storeys?office building?having?9.15?m span.?Seismic?design criteria of Eurocode 8?Ductility Class High (DCH)?with behavior factor (q) of 6.5 and AISC/ASCE code,?Special Moment resisting Frame (SMF) with response modification factor (R) of 8 were employed.?The design outcomes?are?expressed in terms of frame performance?(non-linear analysis), section profiles?(code recommendations), strength-demand to capacity ratios, drift-demand to capacity?ratios and structural weight. The consequences of the research compare?two codes in term of weights and design performances.?This will aid professional engineers and researchers to select effective design criteria and capacity design rules?efficiently.

Design and Fabrication of Aluminum Cladding and Curtain Wall of a Sports Club

The paper discusses the design, fabrication and the execution of the cladding supported by steel trusses and curtain wall of a sports club. The cladding and the curtain walls were subjected to a wind load of 1.2 Kpa considering basic wind speed of 25 m/s as per the project specifications. The first part of the paper deals with the cladding work of the canopy that consist of a 4 mm thick aluminium composite panels supported by steel trusses extended from the main structure. Two types of steel trusses were provided, the main truss connected to the space truss, whereas the intermediate truss connected to channels. Both trusses were spaced at 2.5 m centre to centre. These trusses were fabricated at factory and transported to the site for installation. The second part of the paper is related to the curtain wall design having Maximum Mullion spacing of 2 m, considered as worst scenario for the design calculations. The maximum Mullion height was 5.55 m, adopted in the calculations with bottom and top pinned connection. The Technal system was adopted for the design of mullions and transoms. Design was carried out using numerical modeling with CSI SAP2000 for cladding and its supporting structures. The bracket was realized and checked for the corresponding induced forces. All the structural systems were found safe according to different acceptance criterion.

A standard formulation for the installation of suction caissons in sand

Suction assisted installation of caisson foundations in sand relies on the developed seepage around the caisson wall.Seepage is known to produce soil loosening inside the caisson cavity and an overall reduction in soil resistance to caisson penetration.On the other hand,suction must be controlled so that no excessive piping is induced within the sand volume trapped inside the caisson cavity.When it extends over the full embedded length of the caisson wall,piping may lead to the formation of piping channels,which may compromise the established seal between caisson and soil and ultimately cause the installation process to stop.A safe installation process requires a proper design procedure to ensure that a safe suction can be predicted prior to installation.The present paper provides a framework where analytical expressions are obtained for the required suction magnitude,and for the critical suction that causes piping to initiate at the caisson tip.These analytical expressions are derived for a normalized caisson geometry,based on compiled results obtained from finite element analysis of seepage around a caisson wall,at various installation depths.The developed analytical formulation applies independently of caisson dimensions such as diameter,height and wall thickness.Critical suction for piping condition is also obtained under analytical form as a function of normalized penetration depth.The developed formulation can also be easily incorporated into design procedures or used in design codes without a need for a preliminary seepage analysis to be undertaken.The proposed suction predictions for the whole process of caisson installation in sand are validated against field trials reported in the literature.