Abstract: Many multi-box corrugated steel web low tower cable-stayed bridges have been built across the world，but single-box multi-chamber low tower cable-stayed bridges with corrugated steel and concrete composite webs are still rare． The shear lag effects of this new combined box profile sections need to be further explored． At present，the commonly used analytical methods for designing the analysis of shear lag effect mostly adopt plane beam model，single beam model，solid model，etc． But these calculation models lack refinement when analyzing various stress indexes of shear lag effect． The spatial grid analysis model can make up for the shortcomings of these analysis methods． Therefore，the spatial grid analysis method was adopted to discuss the shear lag effect of low tower cable-stayed bridges with low towers in this paper． Firstly，the principle of shear lag effect，the method of spatial grid a-nalysis and the feasibility of the method verifying the space grid analysis of corrugated steel webs were analyzed in detail． Then a single-box multi-chamber low tower cable-stayed bridge with corrugated steel and concrete composite
webs was taken as a typical case，and its shear lag effect was analyzed by a spatial grid model． The results show that，firstly，the top slab of this type of box girder shows obvious positive shear lag，and the bottom slab shows small positive shear lag; secondly，the effect of positive shear lag at the concrete web is significantly greater than that at the corrugated steel web; thirdly，the shear lag coefficients show a certain change law． Through case analysis，the distribution law of shear lag coefficients in key sections of this type of steel-concrete composite struc-ture along the horizontal and vertical directions was obtained，which can provide a reference for similar projects．At the same time，the validity and accuracy of the spatial grid analysis method is verified． The spatial grid analysis model makes up for the shortcomings of conventional analysis methods and brings new ideas and directions for the refined design of bridges．

Key words: shear lag coefficient, low tower cable-stayed bridge, space mesh analysis method, corrugated steel web, concrete web, composite web