Entity

Time filter

Source Type


Poursha M.,Sahand University of Technology | Khoshnoudian F.,Amirkabir University of Technology | Moghadam A.S.,Structural Engineering Research Center
Soil Dynamics and Earthquake Engineering | Year: 2014

This paper aims to extend the consecutive modal pushover (CMP) procedure for estimating the seismic demands of two-way unsymmetric-plan tall buildings subjected to bi-directional seismic ground motions taking the effects of higher modes and torsion into account. Multi-stage and single-stage pushover analyses are carried out in both X and Y directions. Inelastic seismic responses obtained by multi-stage and single-stage pushover analyses for X and Y directions are combined using the SRSS combination scheme. The final seismic responses are determined by enveloping the combined results of multi-stage and single-stage pushover analyses. To evaluate the accuracy of the proposed procedure, it is applied to two-way unsymmetric-plan tall buildings which include torsionally stiff and torsionally flexible systems. The results derived from the CMP procedure are compared with those from nonlinear response history analysis (NL-RHA), as a benchmark solution. Moreover, the advantages of the proposed procedure are demonstrated by comparing the results derived from the CMP to those from pushover analysis with uniform and fundamental effective mode distributions. The proposed procedure is able to accurately predict amplification or de-amplification of the seismic displacements at the flexible and stiff edges of the two-way unsymmetric-plan tall buildings by considering the effects of higher modes and torsion. The extended CMP procedure can accurately estimate the peak inelastic responses, such as displacements and storey drifts. The CMP procedure features a higher potential in estimating plastic hinge rotations at both flexible and stiff sides of unsymmetric-plan tall buildings under bi-directional seismic excitation when compared to the uniform and fundamental effective mode force distributions. © 2014 Elsevier Ltd. Source


A cooling system is an integrated part of a power plant with steam cycles. Ambient winds can significantly alter the flow field around a natural draft cooling tower which reduces the plant's efficiency. On the other hand, a wind load is extremely important in structural design of natural drought cooling towers (CT). In this paper, a method which utilizes a variable height for towers is introduced to reduce the structural design wind loads. This method reduces the height of the CT under high speed crosswinds. In order to examine the validity of the proposed method, a real scale CT is selected as a case study and the structural design wind loads as well as the thermal performance of the selected CT are analyzed for both the whole and reduced height towers. The structural design wind loads are calculated based on German guidelines, and the CT thermal performance is evaluated by Computational Fluid Dynamic (CFD) model. The numerical results confirm the validity of the proposed method in which the structural design wind loads are properly reduced without considerable reduction in the thermal performance of the CT. This method can be used for effective natural drought cooling towers design. © 2013 Elsevier Ltd. Source


Guru Jawahar J.,Jawaharlal Nehru Technological University Anantapur | Sashidhar C.,Jawaharlal Nehru Technological University Anantapur | Ramana Reddy I.V.,Sri Venkateswara University | Annie Peter J.,Structural Engineering Research Center
Materials and Design | Year: 2013

This investigation is mainly focused on the development of cost-effective normal strength M 25 grade of self compacting concrete (SCC) for the use of normal building constructions. Keeping in view of the normal strength, cost, quality and durability of SCC and greenhouse gas emissions, a combination type of SCC was developed with 35% replacement of cement with class F fly ash. This study recommended a SCC mix with moderate fines to obtain a cost-effective normal strength SCC for the normal building constructions. Studies also revealed that further reduction in fines content in SCC with the same replacement level of fly ash decreased the SCC strength and its performance. Cost analysis has been done between M 25 grade of SCC and conventional concrete (CC). Results shown that the SCC material cost is slightly higher than that of CC of the same strength class, but the savings in labour cost and construction time and quality of SCC would offset the SCC material cost and reduce the total life cycle cost of SCC. © 2013 Elsevier Ltd. Source


Badri R.K.,Islamic Azad University at Tehran | Nekooei M.,Islamic Azad University at Tehran | Moghadam A.S.,Structural Engineering Research Center
Journal of Earthquake Engineering | Year: 2015

This study primarily investigates if the building asymmetry changes the variance of collapse capacity. The example models are five-story reinforced concrete buildings. The variance of collapse capacity is evaluated by first-order-second-moment method. There is a difference between the results of symmetric and asymmetric building models, independent of torsional behavior. The influence of record-to-record variability is more important than the effects of modeling uncertainty on the variance of collapse capacity. Plastic rotation capacity is the most important contributor to the variance of collapse capacity of high ductile buildings independent of the asymmetry. © Taylor and Francis Group, LLC. Source


Guru Jawahar J.,Jawaharlal Nehru Technological University Anantapur | Sashidhar C.,Jawaharlal Nehru Technological University Anantapur | Ramana Reddy I.V.,Sri Venkateswara University | Annie Peter J.,Structural Engineering Research Center
Materials and Design | Year: 2013

This investigation is mainly focused on finding the unit weight, compressive strength, modulus of elasticity (MOE) and splitting tensile strength (STS) of SCC mixes with different coarse aggregate blending (60:40 and 40:60) (20. mm and 10. mm) and coarse aggregate content (28% and 32%) and these properties were compared to a conventional concrete (CC). All SCC mixes had 35% replacement of cement with class F fly ash. The coarse aggregate blending did not affect the compressive strength of SCC mixes, but it affected the unit weight, MOE and STS of SCC mixes. A new parameter called coarse aggregate points (CAPs) has been introduced to study the effect of coarse aggregate blending in a particular coarse aggregate content on mechanical properties of SCC mixes. It is observed that for the given strength, SCC mixes with the same CAP value have shown similar mechanical properties. The measured MOE of all mixes were compared with ACI 363R and AASHTO LRFD/ACI 318 predicted equations. The measured STS of all mixes were compared with ACI 363R and CEB-FIP predicted equations. © 2012 Elsevier Ltd. Source

Discover hidden collaborations