This may helps you:
<Grid>
<Grid.Resources>
<Style x:Key="GridColumnDefaultStyle" TargetType="ColumnDefinition">
<Setter Property="Width" Value="1*"/>
</Style>
</Grid.Resources>
<Grid.ColumnDefinitions>
<ColumnDefinition Style="{StaticResource GridColumnDefaultStyle}"/>
<ColumnDefinition Width="2*"/>
</Grid.ColumnDefinitions>
</Grid>