Cem Aydemir

Uncertainty Analysis of Flexural Overstrength Ratio for RC Columns

This paper summarizes the results of a comprehensive statistical study of the flexural overstrength ratio for estimation of the probable flexural strength of ductile RC columns with varying geometries and confinement levels. The material and section properties and the analytical model response are modeled as random variables and their effects on section behavior are assessed through statistical evaluation. For randomly sampled values of the considered variables, the sectional analyses are carried out using a computer program that uses various confined and unconfined concrete models to obtain the maximum flexural strength in the moment-curvature relationship. The effect of variability is investigated by examining the response distributions resulting from Monte Carlo simulations. Furthermore, a simple expression is derived for estimation of the probable flexural strength using the flexural overstrength ratio with the 10% probability of being exceeded. Finally, the proposed method is compared with ACI 318, Eurocode 8, and the Turkish seismic design code provisions.

Residual Displacement Demand Evaluation From Spectral Displacement

In this study, residual displacement demands are investigated for SDOF systems with period range of 0.1-3.0 s for near-field and far-field ground motions. The effects of stiffness degradation and post yield stiffness ratio on residual displacements are investigated. The modified-Clough model is used to represent structures that exhibit significant stiffness degradation when subjected to reverse cyclic loading. The elastoplastic model is used to represent non-degrading structures. For inelastic time history analyses, Newmark’s step by step time integration method was adapted in an in-house computer program. Based on time history analyses, a new simple equation is proposed for residual displacement demand of a system as a function of structural period (T), ductility (µ), strain hardening ratio (α) and spectral displacement (S d ).

Döşeme Donatılarının İç Aks Kirişlerinin Negatif Moment Kapasitesi Üzerine Etkisi

Bu calismada, tablali betonarme ic aks kirislerinde plastik moment kapasitesinin gercege yakin olarak moment-egrilik analizi yardimiyla belirlenebilmesi amaciyla bir hesap yontemi tanitilmistir. Deneysel sonuclarla karsilastirilan ve gercekci malzeme modellerine dayanan hesap yontemi yardimiyla, sargili ve sargisiz betonun basinc etkisi altinda dogrusal olmayan davranisi, cekme donatisindaki peklesme etkisi, basinc donatilarinda burkulma etkisi ve tabla donatilarinda degisken birim sekil degistirme dagilimi goz onune alinarak, cesitli tasarim degiskenlerinin kiris moment kapasitesi uzerine etkileri karsilastirmali olarak incelenmistir. Incelemelerde, negatif egilme etkisindeki tablali kirislerin plastik moment kapasitelerinin, dikdortgen kesit kabulu ya da TS500-2000uf0a2e gore belirlenen tablali kesit varsayimiyla yaklasik olarak belirlenmesi durumunda, kapasite tasarimi baglaminda guvensiz sonuclar elde edildigi gorulmustur. Calismada, pratik amaclar icin negatif egilme etkisinde tablali kiris moment kapasitesinin belirlenmesi amaciyla iki basit yaklasim onerilmistir. Onerilen yaklasimlar ile belirlenen egilme momenti kapasiteleri, analitik olarak ve literaturdeki deney sonuclarindan elde edilmis egilme momenti kapasiteleri ile karsilastirilmistir