An algorithm is proposed for the rapid estimation of the influence of model parameter uncertainties on the seismic performance of structures using incremental dynamic analysis (IDA) and Monte Carlo simulation with Latin hypercube sampling. It builds upon existing methods that quantify the uncertainty for structural models with nondeterministic parameters by performing IDA with multiple ground motion records on each model realization out of a predetermined sample. However, their practical application is restricted due to (1) the inability to determine a priori the required number of samples and (2) the disproportionate increase of the number of analyses in realistic multiparameter models. To address these issues, two fundamental changes are incorporated. First, Latin hypercube sampling is applied progressively by starting with a small sample that is doubled successively until the desired accuracy is achieved. Second, parameter sampling is performed on a record-by-record basis rather than maintaining the same model over an entire record suite, thus expanding the model sample size without increasing the number of nonlinear dynamic analyses. Using strong-column and weak-column models of a steel moment-resisting frame, the algorithm is shown to possess excellent scalability, extending the original methodology to be applicable to large-scale models with hundreds of random variables.
In the present study, the use of industrial waste materials for the improvement of corrosion resistance and durability of concrete was investigated. For the experimental procedure, waste material generated by electrolytic manganese dioxide production and iron mill scale (calamine) in different proportions were used as cement replacements. Concrete specimens in various sizes were prepared, while the corrosion resistance was measured on cylindrical reinforced-cement mortars; specimens without additives (reference) were also constructed for comparison reasons. After demoulding, the specimens were partially immersed in sodium chloride solution up to testing. Current measurements and corrosion rate of steel rebars embedded in mortars were estimated, while the compressive strength and porosity of concretes were also measured. The experimental results indicate that additives may be used as supplementary cementitious materials in low replacement levels (5% w/w). Additionally, the additives seem to provide anticorrosion protection on the reinforcement steel against chloride ingress.
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Five different design approaches are compared on a single mid-rise reinforced concrete building, pitting two performance-based designs against three conventional methods in delivering a solution that satisfies different sets of performance objectives. Two of the conventional designs stem from the literature, and they represent 2003 IBC compatible solutions. Another employs yield point spectra to deliver a code-like solution, satisfying the design norms without needing iterations. The final two are based on the yield frequency spectra to offer a design that can satisfy more detailed performance objectives in a single step. Overall, all five methods are shown to deliver what is expected. Conventional methods can safely capture the code requirements, yet they are disadvantaged when treading in beyond-life-safety territory, where Immediate Occupancy or Collapse Prevention objectives cannot be easily satisfied, a problem that is not shared by performance-based approaches.
