Tom qab nkag siab lub ntsiab lus ntawm purlins, cia peb tham txog lawv cov haujlwm tshwj xeeb.
Lub luag haujlwm tseem ceeb ntawm purlins yog txhawb nqa me me ru tsev panels thiab hloov lub ru tsev load rau lub ru tsev truss. Lawv yuav tsum tau nruj nreem sib xyaw nrog lub ru tsev truss los tsim ib tug unified tag nrho, kom ntseeg tau lub spatial rigidity ntawm lub tsev thiab reliably kis kab rov tav loads.
Raws li kev ncua, purlins tuaj yeem muab faib ua ob hom: inverted L-zoo li tus purlins thiab T-zoo li tus purlins. Nyob rau hauv cov nqe lus ntawm kev xaiv cov khoom, zoo tib yam pob zeb los yog prestressed pob zeb yuav siv tau. Thaum lub purlin ncua yog 4 meters lossis 6 meters, ob daim ntawv no feem ntau yog siv. Yog tias qhov ntev ncav cuag 9 meters lossis ntau dua, cov qauv sib xyaw (sab saum toj chord yog cov pob zeb ntxiv, cov tswv cuab hauv web thiab qis chord yog hlau) lossis lub teeb steel purlins tuaj yeem siv.
Thaum txhawb cov chord sab sauv ntawm lub ru tsev truss, purlins tuaj yeem muab tso rau ntawm lub kaum ntse ntse. Kev tso ncaj ncaj muab kev faib tawm kev ntxhov siab zoo dua, tab sis yuav tsum muaj kev txhawb nqa kab rov tav rau sab sauv chord ntawm lub ru tsev truss. Thaum muab tso rau ntawm lub kaum sab xis, lub ru tsev yuav khoov rau ob qho tib si hauv kev ntxhov siab. Yog hais tias lub ru tsev txoj kab nqes loj thiab cov welds tsis ruaj ntseg, nws yog feem ntau overturning. Yog li ntawd, ib tug luv luv steel phaj yuav tsum tau pre-welded rau lub embedded ib feem ntawm lub sab sauv chord ntawm lub ru tsev truss ntawm kev txhawb nqa los tiv thaiv overturning.
