问题描述:结构分析设计中经常需要考虑P-Delta效应,ETABS中是否可以全面考虑P-Delta效应?是如何考虑的?在设置P-Delta分析中需要注意哪些问题?
解答:
1、P-Delta效应的二阶方法
P-Delta的二阶方法即在结构分析阶段考虑P-Δ贡献,原理就是计入了竖向荷载下的几何刚度;在构件设计阶段考虑P-δ贡献,即对于混凝土偏压构件,根据混凝土规范来放大设计弯矩值。
2、ETABS对P-Delta效应的全面考虑
ETABS2013可以全面考虑结构的P-Delta效应,其具体的考虑通过三个方面体现,1)给出结构的刚重比;2)在分析阶段考虑P?Δ贡献;3)在构件设计阶段考虑P-δ贡献。
3、刚重比
ETABS根据结构总信息中设置的结构体系进行刚重比的计算,其计算结果可以通过表格的方式查看。用户可根据计算得到的结果判定是否考虑P-Delta效应。
框架结构刚重比输出
框剪结构刚重比输出
由于规范计算刚重比计算的方法有一定的近似性,我们推荐使用线性屈曲分析计算结构的整体稳定性及对结构是否要考虑P-Δ效应进行评估。详细内容可参考文献[1]。
4、P-Δ分析选项
ETABS提供P-Δ分析选项,实质就是考虑竖向荷载下结构的几何刚度,其对话框如下所示。一般情况下采用基于荷载的迭代方法,可逐个构件的考虑P-Δ效应,高效地捕捉局部屈曲。
P-Δ分析选项对话框
迭代的荷载工况由用户根据工程实际自行填写,用户的输入工况会影响结构的P-Δ效应。荷载工况通常和结构设计荷载组合相关,如结构设计中考虑下表所示的荷载组合,则我们可以保守的指定P-Δ效应荷载组合为1.2DL+1.4LL。
![](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAhUAAADsCAIAAABMhMPRAAAZ2ElEQVR4nO3cvW76Tr7HcV9RJCSSZvW/htMgUVlI3AMNVRaUgp6KCwCloaGiONJWKxcUUapU262UrJQuzVbnFH6a8Tx45ovNwy9v66WIBIPHX5v52B6T5P+YmJiYmJjip+TaDWBiYmJiusuJ/GBiYmJikkxFfvzP3/8XAIBAWn68fXzei/tqLQD8YcgPAIAE+QEAkCA/AAAS5AcAQIL8AABIkB8AAIn4/NikyXjrenY9Hs6Ol2v61csHAL9WZH5s0mSwONR/2Y6S5GGeKfNks0Ey2lyo6W3zmM3THRcPST7VsbceJ5ZJiUxtBleUblJbEdraUzrMh+U7Z7NBuazB4vCxHSXqr+oM6SikYQDQkZj8OC4e1PAoO1+jQ9yOkkuchbS31t48pZ3l6qzHSZKka/21dQBs0ryDds5gMvOjvT364pqJVS09mw0SPcWz2aB8trVhANCRiPxYj82OKZsNbB2i7RrXczl12PS2eRzNKxq5rfPgYztSu12zF857/2qlBPnR2p6qJeOtcv5R1lON5E2qhdnHdhTesB42BIDfKTw/tiOtz8o5OsTj4sEy8+fbx+cN5Udz7ZQO2tYLaycBfeVHcSbRzI/8nKP6yyZNlKUf5qm/5VbkB4AzBedHc+Qj5+oQtVEQtau60fxonDDZeuHDfFifBNi7aWVwQp3qurW0p0oCIz/ypRfptR6ns/mwHv8YNy8quvKjpw0B4HcKzY9D3WGpfPmR/71xqeQm80MZP8gJ80MhOP84LkblU2Z+1EvMZzsuHvLGKK/yN6y/DQHgd+o3P56Nqdumt80TlB/a9Z/cNa5f2e770lJtPU6SwWJdtLa4orUetyffmzLmweAHgK70fv2qv96qm/zYpI7xm9jxc/06knz8/PPNev7xUd6XVW6Fw3xouU/X3TBiA0C3osbPzbtyXR2iNth+u/mhDXsoARB//+5hPnyYL84c/1DfzfYFDv3l1lMNe8OyXjcEgN/pnPt3leHiRmfn/Y56h033zmBt3nZU/locvytTvnbW7w+qnb79C4btdz21tEflyI/mpbbGxStpwwBAIvL7g467cnXZbHAD3x8EAPTpzP9fYrqp/18CAOhL/P9PPC4efP8/8XJXS8gPALgi/n87AECC/AAASJAfAAAJ8gMAIEF+AAAkyA8AgAT5AQCQID8AABLkBwBAgvwAAEiQHwAACfIDACBBfgAAJMgPAIAE+QEAkCA/AAAS5AcAQKKZHwAABNLy4+v7517cV2sB4A9DfgAAJMgPAIAE+QEAkCA/AAAS5AcAQIL8AABIxOfH6zSZ7F3P7iZPy9Plmn718gHArxWZH6/T5HGV5Y9Pq2GST2pmvC8fk/T1Qk1vm2efJsnw5d05g20VdpPEMimRqc3gjlJJe0rZy1P1zp7FBbXkdWpujvKFnrDfp+UbWxustPB9+VjO+rjKlBeWu0o1wzSVlw7AzYnJj9NqWIXH9z4tH+8mSZJMd/Wc+9TXMXXZ9JbWuru/llU4rYaJkoKv07z7c85ge/NlY7nt7dEXp3avnsW1tsTIj7rrP62G2oarvC8fy3Za399ooV7A9+VjUh9nFH8pn20vHYD7EJEfu4nape71wNB7BNs1rudy6rDpbfMo/aDJswpmH5f3/tVKCfKjtT1VSyZ79fyjZXHR+aGl+25ibY9aDfOE0tbC16l2NvM6bR5SRJSu+10FQB/C82Of2o9VfywnHM4D258byg/PKtj6OO0Qu6/8KI7Te8wPfdNkL0/6iYKxsqfVUDsUcLQwP+eo/vI6TZRWZS9Tf22tyA/gxgXnhzryYT7VPNvQDlrVjuBG86OxCrY+Lnt5qg+xHZ2gfeykTqaW9lT97Nn5oQxCqNPjKmtsR/dmLdZFf9bZwqI+RTLtJtNlnUzvy4nyJt786GlXAdCH0PxwHahql7a1PxYdZeNCxE3mh7EK0vxQxJ9/nFZp+VSP5x8R+TFdvjxpAzaeFqotyWc7rYZ5uZRX+Rvc364CoA/n5od2aaJWdJTPxtRt09vmCcoPyypc4/qV7dwlYHGC/Ghcv7LdB1WPdSlXonwtrFbhcbUr6llc0dpN2rP5SxnzYPADuBfnXb96nTp6w/r6VX99QTf5YV0Fyfi5fpVGPn7+8xV0/lEurrUlwvFz/YZmI2PswZPfl1XuJ9nLk+U+XXeDiQ3gvkSNn+uD5NqYQbP3VAfbbzc/XKsQf/9u9vKkL6jf/KgXZ39q5Rz/CL5/t2yA/TsrjhMXfQWtpxre0pEfwB0R3r9bHFoqU+v9u3003TuDMoZcN2aflr+6VsE6Bq52oI5B8tZ7ilrao3J+f1BfnLQl1u8PNloS/v3Bxt+1i4GNi1fiBgO4QZHfH3Tewqt6Xz7ewPcHAQB9OuP/l9jd1P8vAQD0Jf7/Jza/UKbRvqPef9OvXj4A+LX4/+0AAAnyAwAgQX4AACTIDwCABPkBAJAgPwAAEuQHAECC/AAASJAfAAAJ8gMAIEF+AAAkyA8AgAT5AQCQID8AABLkBwBAgvwAAEg08wMAgEBafrx9fN6L+2otAPxhyA8AgAT5AQCQID8AABLkBwBAgvwAAEiQHwAAifj82KTJeOt6dj0ezo6Xa/rVywcAv1ZkfmzSZLA45I+Pi4ckn9J1PU82GySjzYWa3jbPdpQkD/PMOUO9CnXsrceJZVIiU5vBHaWm8oWeiN2OyjfWa1j/vVodTzOCWrhJbZuprWKlw3xYvnM2G5TLGiwOSlPLXaWaIR1JSwfgBsXkx3HxUIXHx3ZUPl6PG33BduTrIrtsektr9Q7XoK+CmoLHxYPag2/SZkw2ZrC9+Uxfbt3hHhcPWuJWlOg9Lh7qGmazQbkWjeV6mtHaQjM/2iumF6SZqdVKZbNBUh9nFH8pn20vHYD7EJEf67Hac2V172Be0bJd43oupw6b3jaP0vOaNlulE9+O/P1y3rdWKxWdH1qmrse2VqnndtoBvto2/fSu2/xorVi1LuOt0ryy8epBwybVz0q3o4jSdb+rAOhDeH5sR9ajZuvRtPMQ+/OG8qO5dkr3Z+vjtEPs2PzQC3KYD/XD88+3D6PPVeKkXvRx8aD22lfIj+JMopkf+TlH9ZdNql6CO8xTf22tyA/gxgXnh350nCuvs5tRoR0mqx3BjeZH44TJ1scd5sP6ENvRCdrHTpLhbK5Xz1bM/D2r1jYypnjnxqui80MZnFCn+m1bKlYlgZEfeX2KPWE9Tmd1+7PZWGm2Nz962lUA9CE0P+yHzB+f5ehoI0LqbqhxIeIm80O5Op+T5odCP//YBOTHRzXQYhlhLnrkxuDEhc8/jouRGm+NS5TVEvPZqiEc5VX+hvW3qwDow/n58WkbMC+6oWdj6rbpbfME5Yd2dSXX+fUr/dqUpfP98DWgHnnSrwtdOD9sZ1da7q7HSTJYrIt6Fle01uP2bH5TxjwY/ADuxVnXr0rm0Eh9/aq/vqCb/Niklhkk4+f6VRrB+LnebCVgmq8NakZrC+Xj559vrgjMz5/K/eQwH1ru03U3jNgA7kvU+Ln9rlxbV6Ilyu3mhzbsoXSv8ffvHuZDfUGC+3er0pk3vybqvVj1gjzNsD+1OHP8w7vRjZdbTzW8pSM/gDsivX9XuVJvvxW1/2+HteWHMlasHcsXvxZHx8qUr511DFxdR8cgefs9RbbvD9btqb5+4fpaX6MlnmZIW9hSMZXrElzjYmDj4pW4dABuUOT3B30HzpVsNriB7w8CAPp0xv8vsbup/18CAOhL/P9PbHyFTadd4+q/6VcvHwD8Wvz/dgCABPkBAJAgPwAAEuQHAECC/AAASJAfAAAJ8gMAIEF+AAAkyA8AgAT5AQCQID8AABLkBwBAgvwAAEiQHwAACfIDACBBfgAAJJr5AQBAIC0/vr5/7sV9tRYA/jDkBwBAgvwAAEiQHwAACfIDACBBfgAAJMgPAIBEfH68TpPJ3vXsbvK0PF2u6VcvH0r7NEnS16s3A8DlRObH6zR5XGX6H7OXJyVR3pePF+pHAvJjnybJ8OXdOcNpNUzyqY693SSxTEpkajO4o9RUvrA1Yt+Xj/WbexYX1JLXqW1zhFdmurMurpoeV9n3Pk2SxJYf4loBuH0x+XFaDY3w+HqdGl3DPm3vIrtpektrkyTx9ZL7tFyd3UTrKPPX1r1hvo6eGWxvvtSXW6fsaTVU38pWz2abPYtrbYmZH7GVUTeusbjdJF8X9/lHe60A3KWI/NhNzF5gn072+vnHz9e3/RrXczl12PS2ed6Xj+5e8nWvdOJ692d2eXmfW61UdH5ombqbOFp1Wg2t0dttfrRW5vSeKS/354e9gFEt7GHfAHAB4fmxT5tHze/Lx+muef3q5+vbd4h9Q/nRXDul47Z1edo5Smx+6AXJXp7My4DFpb+X8sJRUK/dT354tqO2uPflpFqLPD/KK2/q2gWff5AfwH0Jzg9j5CN7meYdriU/9FEQtV+40fwIOMrOXp7qoQtHn2gfIUieli969WzDSPnJxzDvkU+roXp9KTo/igEJ21hFaGXKdbHkh+0N8yU+LU/GWZQ3P3raNwBcQGh+NA+ZT6u07H1c+ZF3T43rEjeZH8WJVP0XaX4o9POP14D80P+4myi987XOP4qRfNfAj3n+YT72tbC/fQPABQjzw3agrXbBRff0bEzdNr1tnqBesjqRqnV+/ep1mjSuX5k3I3ky5mr58RNyZa+cLS4/et03AFyA/PpVxX/9qr+uoZv8eJ1aZpCMn6sH4z+S8XP9so9WVc/iWlvSQX74bzzbp5N9ZH4ULSQ2gLsWNX5uvyvXlh9ap3O7+aENeyjdbvz9u9nLk74gyf27yjWrlqP+enH2p1bnj3/YN67l/t3814j8UGtFfgD368z7d3++rPnh/Y56h033zqCMIdeN2aflr9nLU6N3zdfOOgaudrWOQfL2W4xs3x+s2/P1/VN/c1B5N8/ipC1pqUyZl4Er/rQ81W+YvqqP5bUCcPsivz/o+eJb7X35eAPfHwQA9KmD/1+iu6n/XwIA6Ev8/088rYa+/594uUsT5AcAXBH/vx0AIEF+AAAkyA8AgAT5AQCQID8AABLkBwBAgvwAAEiQHwAACfIDACBBfgAAJMgPAIAE+QEAkCA/AAAS5AcAQIL8AABIkB8AAIlmfgAAEEjLj7ePz3txX60FgD8M+QEAkCA/AAAS5AcAQIL8AABIkB8AAAnyAwAgEZ8fmzQZb13PrsfD2fFyTb96+XC3tqMkGW2u3gzgjkXmxyZNBouD+msxVbGRzQYX+lgG5Md2lCQP88w5w3Hx0Gz/53qcWCYlMrUZ3FFqKl/YGrHZbFC/uWdxQS3ZpObmaG+JrTJVSfOpLGzZ2iRJBouDMkO5q1QzpCNpg2M2Zbq21kdrVdFId2WiNy7wC8Xkx3HxoIbHRzYbq79WtqP2LrKbpre0VuvmbO0sV2c91vqd/LV151LEpHsG25vP9OUe5sOiPzouHtS3atikljZ7FtfaEqM7DmiJqzLZbFC2TV+uOVvS2FUG5bPxDY7elGq/byxuPc5b4j7/aN+4AD7fovJjPdY/VPbjxOIp89jtuZw6bHrbPEp/Z2nkVuk69d7E7EHyLqxaqej80DJ1PXa06rh4sEZvl/kR0BJnZdTH+onmJtXOVDapFrcf21F46ez7lXdTHjPtnNibH/YtHlXSHnZm4B6F58d2pB+rlmf6tgNY9yH2DeVHc+2U7s/Wg2iH2LH5oRfkMB/qh+d1a0fz8jpMUCcY3x0HtcRZmboIx8WDdoiQzQZKmzepenXoME/9tfU1OGpTmjuetjj1jDnPj/LamlqE4PMP8gO/XHB+NEY+PrLD8fMt74AsFxa0g1P1Y3aj+RFw0HqYD+tDbEcXY7/gngxnc2PcyOy1j4uHZPiQd3DHxYNa1ej8UAYhGpf+zREsf34Yp5LFOhqvOsyHVb6ux+msTib9Omdsg4M3pf2Aph4XabxhvsTh7Gic9nnzo6edGbhHofnhO1C1nG3Un/bGaf5N5odydb5eI0l+KPTzj5BeW//jeqx0dh2ef8Tlh1GZKhs8gzTHxWie1Z1y/qu4wdGb0jNSZZ5/mI99LexvZwbuURf5Ybltt/i0PxtTt01vmyeo09GuruQ6v36ljwfUI9gqT8/ebX60tsRdmXoMTL9CVZdosFgXryquaJXj1dIGx2zKvPKtlyLL2eLyo9edGbhH4utXGmt+5J/A/j5p3eTHJrXMIBk/b9yNFj9+rl9F0Xp2z+JaWyIYP3dWxhgLaWRPfqNauZ/k1zab80Q3OHhT1o303ymXD+ZH5UfRQmIDUEWNn9vvyj3Mh7aOpv4M325+aBf3lV4s/v5dowiS+3eVa1YtB9H14uxPLTzDCUF3Etsrow6SW7+QoRfceiAf3+CgTWnW2bG48hQqIj/UjUt+ABXx/bvm98gU3u+od9h07wzKkGzdmO2o/LU4OlamfO2sY+DqOjoGydvv2LF9a69uz9vHp/pdPP2rFfbF9dQSV2Xat7txyatx8Ura4JZNqXyPNWRLDWfH+g1HG/WxvKTALxT5/UHPF99q2WxwA98fBAD06bz/X2JxU/+/BADQl/j/n9j84pim+R31npt+9fIBwK/F/28HAEiQHwAACfIDACBBfgAAJMgPAIAE+QEAkCA/AAAS5AcAQIL8AABIkB8AAAnyAwAgQX4AACTIDwCABPkBAJAgPwAAEuQHAECimR8AAATS8uPr++de3FdrAeAPQ34AACTIDwCABPkBAJAgPwAAEuQHAEBCmB9JkggWJnuVp+mXr1fIKsSupjm/5x0aT3Vb0ouV6Pz3vOsSieuWeKfzS3e/1ZO1tnV+f8FDauvfUWM3aPXHG9kukvwQl7Lb1b5kfkRtNnVmT6Fa956Qqua/3sLOFF4i1wzmKv9hJTqzbv55zLUWlO7uqieoYWA9ZfO37o1nNiZ2b4nd+rGi8yPkEyvePLFN7+/NXety5oc8cH7XB9vc9uJPzo2UKHBv/mNK1FXdwl8e9Wm9ePX2aZKkrxetYUgpxPN76mYGc8jkef/wmUN+lYnLD2stQj75IWsraLrrqd3EtrzJ3j6D8vdWIc3uZO0CG3Dmgjx16LVEna9In+/8vnws6/C4yr73aaL+qs4w3fW/a7lWsKsCdr5d7B9GpZJmfvS970WtbOLo6/wzNx6YfYJrTusD13ues3ad7DDy8fNq+56zwc5sum+G02qo7pqv0+oTbp+hbTU9U2PtGj9dM5uv8rx5SDOEtfXUoYcSyXaMK5eo6NGqned9+ViFR/WXfnetRpU8DwSl67t6ZkF2k7xc7vOPfmrY+Ls6g2ftrPO0vvOX3km2Vi98Btkb+n+VkY9/uH71N66TRldN981g7n+n1TBRDmfCdtDW9pu7lH8nCy9IyMwd1PPs/BCUqHoc+Jm/com+8+OPp+VJ/VUJjO99qh4m91A3VyX93V9U6XqsnrMg5+aHuP2N/PCvplnkkLcN3ECeyDHnDGmD+eYhn7Kv75/ncgoveER+uJbqejZ2h26UKaTpvhls+592FBm/g7aukbkv+rtC/8o23se6+UP2zpb16jQ/QjZ61I7Rd4lCq5Sfc1Qh8TpNlMpkL9M6Wnqrm7+S1pkDSyeuXuinVSvI+3JSnbrl+VFeAFRP6Xqrofp38wMrWIR1Bs8DAWs7zY3VuolD1qWv/LA22r8Csg0Q+FaC/MhenuqjyDN20NbPradcjdnU93R9dEOWJf9495Mf/hKZf/TM02uJQqtU7DzFwcduMl2+PNXjHxP1WtaFdi3/zILSCaoX+mnNT/2r6VHLj+IjeVoN1TO8i+x7nlKYRXNN/jZ4Chj1zv6t7y9I669qZvSeH62PzflDqhPrivnx1bZbBG5C1/tYd+vwP8bp7fzDU6KvmB3j+iVqVOO0Sl/e6/4u//UidfNUwFPkkNL1W72W8w/z8SX2vdbZ/IvwzxCyiNiqCvLDP+WzNa5Z3WJ+iEvmb7pvhq6vX7lW5JL5YW57/8fb2h2HFKr9qY5KFPKh6rVEoVWq9p/H1a64WlVc0SqHgi9aN3O9OsmPXnYwX0E6y4/zP54hK9I6j7ncqoCullh7dv/WjG2M59dnYwoseK7f61chvYP1/QOb7ptBMn5uXIgIaHnrDuqvkrqfNWaLLan1qfZieurQf4lC9pBeSxRapVx+F195+SV7eUoS2w2ml62bWgpXlxFYOsHGCiqdpSD5HQdR+dFBDaN+DV+KWRD/Lhf4bq3rEti3+H8VxEal3/OPkN7BtQFCmu6bIf7+3ezladi4EBHQbME6Wmf2v4+5r5i9RuAmaCmUWod+SuTfbWL7r/NLFLPJ3pePSV0B1zFyz7uWtZ6ep0Lq3OMOZivIbpL/GpEf59cwamcTLCi2P7TWvFF//8ujmup5+S3mh3xvC2666ynrV5bUnc/+nSbH+XLUJzx2Hc9588bj2A+Dvw79lchsdtTHptsSxW6vxq1W5sWrK+5a5grGvn9s9UJK5yjI0/JUfxMzfVUf91tD8aaPmj9k81W/eh6EvDywAVEvD9Tj9Su1FoEviW36+esfsr6eOvhfErLWrh3F9f6ePayP/aOnEnleG/KXrkp0ySqdX7eQpp65d0VVL6Q9//nXv//zr3/391i878m6oKj5/Z/9xmNXpyGrfx/rbsX/bwfQl+9//PO/f/sr7/H/+7e/un189bUD+QGgR3mE/Pdvf33/45/dPiZCro78ANCvvMfv7zGuhfwAAEiQHwAACfIDACBBfgAAJMgPAIAE+QEAkCA/AAAS5AcAQIL8AABIkB8AAAnyAwAgQX4AACTIDwCABPkBAJAgPwAAEuQHAECimR8AAASq84OJiYmJiSlq+n8y8vyu0cr0XAAAAABJRU5ErkJggg==)
5、P-δ效应的实现
ETABS 2013根据混凝土规范6.2.4条的规定来考虑P-δ贡献,其具体的数值可以在设计细节中查看到,如下图所示。
ETABS还可以将构件进行细分,在分析过程中考虑P-δ贡献,构件细分,比如将柱子都细分为两个以上的对象,可以捕捉到柱子的P-δ贡献。由于在设计过程中已经考虑P-δ贡献,一般情况下不需要使用构件细分来考虑。
参考文献
[1] 李楚舒,李立.结构设计中如何全面考虑P-Δ效应[J],建筑结构,2014,44(5):78-82.