Çelik yapı uygulamalarında kullanılan tüm kaynak yöntemlerinde, kaynaklanan metalik malzemenin kaynak bölgesinin, metalin erime sıcaklığına yakın bir sıcaklığa kadar ısıtılması gerekir. Böyle bir ısıtma işlemini izleyen soğuma, metalde içyapı değişikliklerine neden olduğu gibi, “yüksek sıcaklık, kaynak metali, cüruf, esas metal ve ortam atmosferi” arasında birtakım kimyasal reaksiyonların oluşmasını da kolaylaştırır.

It may appear to be an impossible challenge to try to bridge fire engineering to architecture and further on to sustainability. Nevertheless this is being done as new and credible developments in fire engineering permit the architect to get rid of really now old fashioned fire resistance requirements. This means however that structural components may now remain visible and unprotected, which not only represents a quantum leap for good architecture, but constitutes also a real advantage in favor of solid sustainability.

Makalenin sunum dosyasını indirmek için lütfen tıklayınız.

Bu makale, çelik yapı tasarımını olumlu yönde etkileyen çelik üretimi ve tasarımı üzerine yapılan araştıma projelerindeki en son gelişmeler ile birlikte QST çelik profillerinin verimli ve ekonomik olarak uygulamalarını özetlemektedir.

Günümüz koşullarında artan ulaşım kapasitesiyle birlikte ortaya çıkan park ihtiyacı mühendislerin çalışma konuları içine girmiş ve artan araç sayısına karşı sınırlı park alanı ile birlikte minimum alanda maksimum araç sayısını elde edebilme mantığı mühendisleri çok katlı otopark yapıları tasarlamaya yönlendirmiştir.

Currently in many areas of North America, special permits are issued to extra heavy vehicles without a detailed evaluation of individual components, considering only the ultimate capacity of the bridge inventory as a whole.

In this research, the seismic performance of a proposed efficient energy dissipating steel-braced frame (EEDBF) in relation to that of a moment resisting frame (CBF) is studied.

This paper presents a simple yet efficient physical theory model that can be used to simulate the in elastic cyclic axial force-axial deformation and axial force-transverse deformation relationships of steel braces.

In this study a nonlinear structural model is developed to simulate the cyclic axial force deformation behavior of steel braces including their buckling behavior using the commercially available nonlinear finite element based software ADINA.

The study is aimed at compering the seismic performance of steel chevron braced frames (CBFs) with and without fluid viscous dampers (FVDs) as a function of the characteristics of the near fault (NF) ground motion and FVD parameters.

This paper is focused on a proposed seismic retrofitting system (PRS) configured to upgrade the performance of seismically vulnerable reinforced concrete (RC) buildings. The PRS is composed of a rectangular steel housing frame with chevron braces and a yielding shear link connected between the braces and the frame. The retrofitting system is installed within the bays of an RC building frame to enhance the stiffness, strength and ductility of the structure. The PRS and a conventional retrofitting system using squat infill shear panels (SISPs) are used in an existing school and an office building. Nonlinear time history analyses of the buildings in the original and retrofitted conditions are conducted for three different seismic performance levels (PLs) to assess the efficiency of the PRS. The analyses results revealed that the building retrofitted with the PRS has a more stable lateral forcedeformation behavior with enhanced energy dissipation capability than that of the one retrofitted with SISPs. For immediate occupancy PL, the maximum inter-storey drift of the building retrofitted with the PRS is comparable to that of the one retrofitted with SISPs. But for life safety and collapse prevention PLs, the maximum interstorey drift of the building retrofitted with the PRS is considerably smaller than that of the one retrofitted with SISPs. Furthermore, compared with the building retrofitted with SISPs, the building retrofitted with the PRS experiences significantly less damage due to the more ductile behavior of the system at the life safety and collapse prevention PLs.

In this paper, analytical equations are developed to estimate the lateral displacement
capacity of steel-H piles in integral bridges with stub abutments subjected to cyclic thermal variations. First, steel H piles that are capable of sustaining large plastic deformations are identified based on their local buckling strength. The normalized moment–curvature relationships of these piles are then obtained for various axial load levels. Next, a low-cycle fatigue damage model is employed to determine the maximum cyclic curvatures that such piles can sustain. The obtained moment–curvature relationships and cyclic curvature limits are used in static pushover analyses of two steel H-piles driven in soil to obtain the maximum thermal-induced cyclic lateral displacements such piles can sustain. Using the pushover analyses results, the displacement capacity of steel H-piles are formulated as a function of pile’s properties, soil type and stiffness. Based on the obtained pile cyclic displacement capacities,
the maximum length limits for integral bridges subjected to cyclic thermal variations
are calculated. It is found that the maximum length limit for concrete integral bridges ranges between 150 and 265 m in cold climates and 180 and 320 m in moderate climates and that for steel integral bridges range between 80 and 145 m in cold climates and 125 and 220 m in moderate climates.

This study is aimed at comparing the seismic performance of steel chevron braced frames (CBFs) with and without viscous fluid dampers (VFDs) as a function of the intensity and frequency characteristics of the ground motion and VFD parameters. For this purpose, comparative nonlinear time history (NLTH) analyses of single and multiple story CBFs with and without VFDs are conducted using ground motions with
various frequency characteristics scaled to represent small, moderate and large intensity earthquakes. Additionally, NLTH analyses of single and multiple story CBFs with VFDs are conducted to study the effect of the damping ratio and velocity exponent of the VFD on the seismic performance of the frames. The analysis results revealed that the seismic performance of the CBFs without VFDs is very poor and sensitive to the
frequency characteristics and intensity of the ground motion due to brace buckling effects. Installing VFDs into the CBFs significantly improved their seismic performance by maintaining their elastic behavior. Furthermore, VFDs with smaller velocity exponents and larger damping ratio are observed to be more effective in improving the seismic performance of the CBFs. However, VFDs with damping ratios larger than 50% do not produce significant additional improvement in the seismic performance of the CBFs.