某原木柱選用東北落葉松,原木標(biāo)注直徑d=120mm,木柱沿其長(zhǎng)度的直徑變化率為每米9mm,計(jì)算簡(jiǎn)圖如下圖所示。試問(wèn),柱軸心受壓的穩(wěn)定系數(shù)φ與下列何項(xiàng)數(shù)值最為接近?()
A.0.50 B.0.45 C.0.37 D.0.30