所謂增建(二工)預留鋼筋圖說,即建物未來有增建可能時,應於RC梁柱預留鋼筋, (僅供參考,仍須配合實際情況修正)
預拱度(可按照比例推估),以下以鋼樑為例
1.A beam (or truss) 36' long with a deflection criteria of say L/360, would have camber of 1". 2.For example,While a beam (or truss) 4.5' long with the same deflection criteria would have a camber of 1/8" 3.For steel bridges, we can adopt (100% DL + 75% LL) to compute the camber. 4How much Camber? There are certain restrictions for cambering of beams. As a rule of thumb, beams with the following criteria cannot be cambered: Beams less than 24 feet in length Beams in moment frames Beams shallower than 14 inches deep Beams with cantilevered ends PS. Beams shorter than 24 (or 20~25) feet are typically not cambered because they may not fit in the fabricator's machine and also it is not economical or practical to provide such a small camber. Additionally, the AISC specifies minimum and maximum camber values depending on the beam depth and span. For example, the minimum camber on a 24 inch deep wide flange beam spanning between 65 and 85 feet is 3 inches and the maximum is 5 inches. 資料提供: 良泰大地土木結構技師事務所 e-mail:[email protected] tel:06-2363337 現場地坪與地梁之間往往需要有錨定接合的處理,然我國規範與常用的標準圖說卻很少這方面的說明,
鄰近的日本在設計時,這方面的施工圖說相對明確, 本工作室以下以日本設計案例結構圖說明混凝土增灌使地梁地坪連結之方式 (1)常用連接方法請參考以下網頁 http://liangtai.pixnet.net/blog/post/105964954 (2)鋼筋錨定延展長度應參考本國規範(我國規範乃依據ACI規範所制定,與日本略有不同),惟我國與日本設計與施工之概念原則類似 (3)本圖說僅供參考 資料提供: 良泰大地土木結構技師事務所 e-mail:[email protected] tel:06-2363337 圖說完整版請參考
http://liangtai.pixnet.net/blog/post/112973392 以下介紹RC樓板撓度計算(載重:均佈載重,集中荷重or線載重請用有限元素分析程式計算)Consider the floor system shown in Fig. a. Fig. a參考 http://liangtai.pixnet.net/blog/post/112973392 Estimate the deflection of the slab panel identified in part b of the figure under the follwoing conditions. Given: Span length along X-X direction = 30’ (9.14 m) Span length along Y-Y direction = 26.25’ (8.0 m) Slab thickness = 8 in (203 mm) Ec (modulus of elasticity) = 4.287 * 106 psi ( 29,558 MPa) Superimposed dead load = 25 psf ( 1.2 kN/m2) Live load = 40 psf (1.9 kN/m2) Required Deflection of the panel at midspan for the following load combination Superimposed dead load = 25 psf ( 1.2 kN/m2) Live load = 40 psf (1.9 kN/m2) Required Deflection of the panel at midspan for the following load combination 1*DL + 1*LL Aspect ratio γ = 30/26.25 = 1.14 Total service load q = [(20+5+40) + 150*8/12]/144 = 1.146 lb/in2 (7.9*10-3 N/mm2) Using closed form formulas (Table 5) (a4*q / E*h3 ) = [(30*12)4 * 1.146 / (4.287*106 * 83) = 8.77 in (222.76 mm) For mid-panel deflection, consider case 3 from Table A Table A 參考 http://liangtai.pixnet.net/blog/post/112973392 k = 0.0548 Deflection, Δ = k (a4*q / E*h3 )= 0.0548*8.77 = 0.48 in (12.20 mm) For deflection at midpoint of column lines in X-direction, from Table 5 k = 0.0446 Deflection, Δ = k (a4*q / E*h3 )= 0.0446*8.77 = 0.39 in (9.91 mm) 撓度檢核:查表與手算之後再對照我國規範標準檢核 資料提供: 良泰大地土木結構技師事務所 e-mail:[email protected] tel:06-2363337 內容標籤: RC板設計, 樓板撓度計算, 結構設計 |
AuthorL.T. Structure Archives
October 2016
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