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Nassiri H., Khayat Khoie A.,
Volume 3, Issue 3 (9-2005)

This paper studies the effects of queue formation in the bottlenecks at off-ramps on the capacity of the freeways. Six expressway exit-ramps throughout the city of Tehran, Iran were selected and their traffic flows were observed in thirty-minute intervals during which the queue formation and queue elimination occurred. Assuming that in the absence of the queue, the traffic flow is in its normal state, the changes in the volume of through vehicles has been modeled as an average estimator of the change in the expressway capacity.The developed models prove that the changes in freeway capacity are due to queue formation at the off-ramp sections. However, the estimated figures are different from those obtained from the theory of freeway capacity. The conclusion is that lane blockage is only one of many factors that affect the freeway capacity while the queue forms. Since it is not possible to quantify all those factors individually, the resulting models are macroscopic estimates of the phenomenon.
S. Karimiyan, A. Moghadam, A. . Husseinzadeh Kashan, M. Karimiyan,
Volume 13, Issue 1 (3-2015)

Plan irregularity causes local damages being concentrated in the irregular buildings. Progressive collapse is also the collapse of a large portion or whole building due to the local damages in the structure. The effect of irregularity on the progressive collapse potential of the buildings is investigated in this study. This is carried out by progressive collapse evaluation of the asymmetric mid rise and tall buildings in comparison with the symmetric ones via the nonlinear time history analyses in the 6, 9 and 12 story reinforced concrete buildings. The effect of increasing the mass eccentricity levels is investigated on the progressive collapse mechanism of the buildings with respect to the story drift behavior and the number of beam and column collapsed hinges criteria. According to the results, increasing the mass eccentricity levels causes earlier instability with lower number of the collapsed hinges which is necessary to fail the asymmetric buildings and at the same time mitigates the potential of progressive collapse. Moreover, the decreasing trend of the story drifts of the flexible edges is lower than those of the stiff edges and the mass centers and the amount of decrement in the story drifts of the stiff edges is approximately similar to those of the mass centers.
X. Liu, K. Sheng, J.h. Hua, B.n. Hong, J.j. Zhu,
Volume 13, Issue 3 (12-2015)

In order to improve the utilization of high liquid limit soil, the fundamental properties of high liquid limit soil and its direct utilization method are studied in this paper. This work involves both laboratory and fieldwork experiments. The results show that clay and sandy clay both with high liquid limit can be directly used for the road embankment, and the degree of compaction can be controlled at 88 %. The pack-and-cover method in accordance with Chinese technical specifications is recommended to be operated in the engineering practice. The packed height should be less than 8 meters and the total height of embankment no more than 12 meters in the interests of settlement. From the view of stability, the optimal thickness value of top sealing soil layer and edge sealing soil layer is about 1.5 meter respectively, and the geogrid reinforcement spacing should be about 2.0 meters. In addition, based on Yun-Luo expressway in China filled with high liquid limit soil, the construction techniques and key points of quality control in subgrade with pack-and-cover method are compared and discussed in detail, and the feasibility of these schemes are verified by the experimental results.

H. Tekeli, E. Atimtay, M. Turkmen,
Volume 13, Issue 3 (9-2015)

In this paper, an approximate method is proposed for determining sway of multistory RC buildings subjected to various types of lateral loads. The calculation of both fundamental period and stability index in RC building requires the sway term at each story level. Using approximate method design engineers can estimate sway terms at each story level. The developed analytical expressions are inserted into fundamental period and stability index equations to replace the sway terms, which yields modified equations for fundamental period and stability index without any sway terms. It is fairly easier to employ these equations developed by eliminating all sway terms. Results obtained from the equations are remarkably close to those generated by the related computer program. Consequently, design engineers can reliably use the simple equations to calculate stability index and fundamental period, which enables the determination of these parameters without referring to the complex sway terms. The capability and accuracy of the proposed equations are demonstrated by a numerical example in which computer program results are compared with the proposed methodology.

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