Seismic behaviour of spatial structures

In this study, the calculation of the ultimate load of shell structures is proposed based on key structural design parameters such as shell spans, rise to span ratios, roof weights and tube cross sections, achieved by analysing the relationship between the ultimate loads and structural design parameters.

Normally, single-layer reticulated shell structures should be safely designed not to buckle or collapse under design loads. The calculation of the ultimate load corresponding to the collapse stage under the action of earthquakes should consider factors such as membrane action, configurations, boundary conditions, materials, members, nodes, connections between members and nodes, geometric imperfection, load distribution, peak ground motion and the duration as well as frequencies of ground motions.

Stages

Firstly, general single-layer reticulated shell models will be built considering all of these factors in the finite element package ANSYS. After this, the nonlinear time-history response analysis for typical single-layer reticulated shells will be carried out. These reticulated shells have different structural design parameters subjected to 300, three-dimensional, seismic records selected from the database of COSMOS, from seven earthquakes, based on magnitude, distance, focal mechanism, and site class. Then, the relationships between the collapse loads and structural design parameters will be investigated, based on the numerical simulations and existing shaking table tests, using statistical methods.

Following this, the collapse load will be transformed into design loads to design shell structural configurations using an appropriate but relatively high safety factor. The reason for the higher safety factor is that the value of the statistical life is significantly higher when compared with the associated increase in the cost of shell construction, which will increase the safety of the shell structures and substantially reduce the risk of collapse and ensuing fatalities.

Finally, a new seismic failure criterion will be determined for civil engineers to use to estimate the seismic failure load of single-layer reticulated shells based on key structural design parameters such as structure spans, rise to span ratios, roof weights, tube sections etc.

It is envisaged that this research project will result in the submission of at least two journal papers to high impact journals (i.e, Journal of Structural Engineering and/or Engineering Structures).