|
|
مهندسی عمران مدرس، جلد ۱۲، شماره ۲، صفحات ۳۷-۵۰
|
|
|
| عنوان فارسی |
مطالعه تجربی اثر میزان سفت شدگی پیچ های پیونده های گوی سان بر طول کمانش اعضای فشاری سازه های شبکه ای فضاکار |
|
| چکیده فارسی مقاله |
تاکنون تحقیقات اندکی در زمینه مطالعه تجربی اثر میزان سفتشدگی پیچ های اتصالات پیچی سازه های فضاکار بر رفتاراتصالات و پاسخ سازه انجام شده است. در این مطالعه، آثار میزان سفتشدگی پیچ ها بر شرایط سرحدی انتهائی و طول مؤثر کمانش اعضای فشاری به طور تجربی مطالعه شده است. بیش از چهل آزمایش بر مدول های هرمی شکل متشکل از هشت عضو لوله ای با انجام شده است. این آزمایشها با میزان متفاوت سفتشدگی پیچ های اتصالات تکرار شده اند (MeRo) اتصال پیچی از نوع سیستم مروو حاکی از تأثیر قابل ملاحظه میزان سفت شدگی پیچها بر طول موثر کمانش و ظرفیت باربری اعضا در نمونههای آزمایش بوده اند .در این مقاله، ضمن تشریح و تفسیر نتایج آزمایشها، توصیه های اجرایی جهت ارتقاء ظرفیت باربری و اعتمادپذیری سازه های فضاکار شبکهای ارائه شده است. |
|
| کلیدواژه‌های فارسی مقاله |
|
|
| عنوان انگلیسی |
An Experimental Study of the Influence of the Degree of Bolt Tightness on the Effective Length of Compression Members of Double Layer Space Structures Composed of Ball Joints |
|
| چکیده انگلیسی مقاله |
Abstract: A search of the published literature reveals that studies related to the effects of the degree of bolt tightness on the behavior of space structural joints and consequently on the member behavior and the overall response of space structures are rather limited. An experimental investigation of the effects of bolt tightness on the rigidity of double layer grids, carried out previously by the authors, had revealed the significance of the degree of bolt tightness on the overall rigidity of the tested structures. The present research is concerned with an investigation of the effects of the degree of bolt tightness on the end conditions and consequently on the effective lengths and the slenderness ratios of compression members of double layer space structures. An experimental program of work was conducted on more than 40 test specimens consisting of typical pyramidal modules of representative double layer grids to observe the influence of the degree of bolt tightness on the effective length and load carrying capacity of diagonal compression web members of such modules. Each module was fabricated by practically identical tubular members and the matching MERO type ball joints. However, different modular specimens were constructed using tubular members with different diameters and cross sectional properties. In each individual test specimen, it was attempted that the bolts connecting the members to the ball joints be tightened by the same applied torque to achieve an identical degree of tightness in all its joints. However, different values of applied torques were used to tighten different test specimens. Following the preparation of the test specimens tightened with different applied torques, a monotonically increasing concentrated load was applied at the upper node of each specimen. The tests were continued up to failure and in each test the displacement of the central top node just underneath the applied load was measured as the main component of the response of the test module. The observations indicate that the degree of bolt tightness has a significant influence on the effective lengths and consequently the load carrying capacity of compression members of such modules. However, over-tightening may cause failure of connection sleeves. Also, bolt pre-stressing shall not be made to a degree that causes brittle fracture of pre-stressed bolts or premature tearing of member to end cone welded connections under additional applied tension. On the basis of the observed behavior and supporting theoretical studies, the effects of the bolt tightness on the behavior of double layer space structures have been discussed in the context of design assisted by testing emphasized in Chapter 7 of the Iranian Code of Practice for Space Structures. With due consideration of different aspects of the influence of the degree of bolt tightness on the behavior of joints, members and modules, as well as the overall structural behavior, some practical recommendations have been presented to improve the reliability of structural performance through increasing rigidity and load carrying capacity of such double layer space grid structures, that can be achieved as a result of a proper choice of the bolt tightening procedure. |
|
| کلیدواژه‌های انگلیسی مقاله |
|
|
| نویسندگان مقاله |
سیروس غلامپور |
دانشگاه آزاد قائم شهر
شاهرخ مالک |
دانشگاه تهران دانشکده فنی
سازمان اصلی تایید شده: دانشگاه تهران (Tehran university)
|
|
| نشانی اینترنتی |
http://mcej.modares.ac.ir/article_1830_5e603bbc1bb803fade6a345e86ea00bb.pdf |
| فایل مقاله |
اشکال در دسترسی به فایل - ./files/site1/rds_journals/1242/article-1242-225598.pdf |
| کد مقاله (doi) |
|
| زبان مقاله منتشر شده |
fa |
| موضوعات مقاله منتشر شده |
|
| نوع مقاله منتشر شده |
|
|
|
|
برگشت به:
صفحه اول پایگاه |
نسخه مرتبط |
نشریه مرتبط |
فهرست نشریات
|